Answers.Body: <p><strong>Tl;dr</strong>: most likely parts from <a href="https://www.sluban.nl/en" rel="noreferrer">Sluban</a> or <a href="http://oxfordtoy.co.kr/index.asp" rel="noreferrer">Oxford</a>.</p>
  <hr />
  <h1>Original Post</h1>
  <p>@Zhaph is right that the tail fin looks like the one on the Kre-O Starscream:</p>
  <p><em>Yours</em>:</p>
  <p><a href="https://i.sstatic.net/Jy2Dp.png" rel="noreferrer"><img src="https://i.sstatic.net/Jy2Dp.png" alt="Tailfin from OP's question" /></a></p>
  <p><em>Kre-O:</em></p>
  <p><a href="https://i.sstatic.net/CfLon.png" rel="noreferrer"><img src="https://i.sstatic.net/CfLon.png" alt="Tailfin from Kre-O Starscream" /></a></p>
  <hr />
  <p>I started looking for other Kre-O sets that use the piece. I found the <a href="https://consumercare.hasbro.com/en-us/instructions/kre-o?q=Kre+O&amp;q=&amp;hsb_doc_search_button=SEARCH" rel="noreferrer">Toy &amp; Game Instructions</a> page which included sets with strikingly similar pieces.</p>
  <p>The <a href="https://www.hasbro.com/common/documents/6d0a17b55056900b100f781b9c2c69e3/E8E7344650569047F5A337FF4E8E0497.pdf" rel="noreferrer">Kre-O Star Trek USS Vengeance - A4364 Instructions (PDF)</a> cockpit is eight studs long while the cockpit in your photo looks to be about six studs long, but they have the same geometry.</p>
  <p><em>Yours:</em></p>
  <p><a href="https://i.sstatic.net/RJWmp.png" rel="noreferrer"><img src="https://i.sstatic.net/RJWmp.png" alt="Cockpit from OP's question" /></a></p>
  <p><em>Kre-O:</em></p>
  <p><a href="https://i.sstatic.net/EHsQh.png" rel="noreferrer"><img src="https://i.sstatic.net/EHsQh.png" alt="Cockpit from Kre-O USS Vengeance" /></a></p>
  <p>The <a href="https://www.hasbro.com/common/documents/6d0a17b55056900b100f781b9c2c69e3/1D0862565056900B10B3E6AD88A5C4FD.pdf" rel="noreferrer">Kre-O Transformers Battle for Energon - 98812 (PDF)</a> includes six-by-two stud sloped bricks that look like they could match the upside down brick in your photo.</p>
  <p><em>Yours:</em></p>
  <p><a href="https://i.sstatic.net/H35mE.png" rel="noreferrer"><img src="https://i.sstatic.net/H35mE.png" alt="Sloped brick from OP's question" /></a></p>
  <p><em>Kre-O:</em></p>
  <p><a href="https://i.sstatic.net/fq6bW.png" rel="noreferrer"><img src="https://i.sstatic.net/fq6bW.png" alt="Sloped brick from Kre-O Battle for Energon" /></a></p>
  <hr />
  <p>Unfortunately, it looks like the Kre-O inverted slopes (at least in <a href="https://www.hasbro.com/common/documents/6d0a17b55056900b100f781b9c2c69e3/2315118F5056900B1042FAD0FA4C2DC5.pdf" rel="noreferrer">Kre-O Transformers Destruction Site Devestator - 36951 (PDF)</a>) are closer to LEGO's inverted slopes than the ones in your photo.</p>
  <p><em>Yours:</em></p>
  <p><a href="https://i.sstatic.net/jWNKJ.png" rel="noreferrer"><img src="https://i.sstatic.net/jWNKJ.png" alt="Inverted 2x3 slope from OP's question" /></a></p>
  <p><a href="https://i.sstatic.net/P4PvX.png" rel="noreferrer"><img src="https://i.sstatic.net/P4PvX.png" alt="Inverted 2x3 slope from OP's question" /></a></p>
  <p><em>Kre-O:</em></p>
  <p><a href="https://i.sstatic.net/deW8I.png" rel="noreferrer"><img src="https://i.sstatic.net/deW8I.png" alt="Inverted 2x3 slope from Kre-O USS Vengeance" /></a></p>
  <p><a href="https://i.sstatic.net/DkWK8.png" rel="noreferrer"><img src="https://i.sstatic.net/DkWK8.png" alt="Inverted 2x3 slope from Kre-O Destruction Site Devestator" /></a></p>
  <p><em>Yours:</em></p>
  <p><a href="https://i.sstatic.net/Tbqe2.png" rel="noreferrer"><img src="https://i.sstatic.net/Tbqe2.png" alt="Inverted 2x2 slope from OP's question" /></a></p>
  <p><a href="https://i.sstatic.net/j7TGf.png" rel="noreferrer"><img src="https://i.sstatic.net/j7TGf.png" alt="Inverted 2x2 slope from OP's question" /></a></p>
  <p><em>Kre-O:</em></p>
  <p><a href="https://i.sstatic.net/sCXWq.png" rel="noreferrer"><img src="https://i.sstatic.net/sCXWq.png" alt="Inverted 2x2 slope from Kre-O Destruction Site Devestator" /></a></p>
  <p><a href="https://i.sstatic.net/Sim2R.png" rel="noreferrer"><img src="https://i.sstatic.net/Sim2R.png" alt="Inverted 2x2 slope from Kre-O Destruction Site Devestator" /></a></p>
  <p>It's hard to tell if your six-stud-long slopes are curved or not, but they look closer to <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=42022#T=C" rel="noreferrer">LEGO Slope, Curved 6 x 1</a> than they do the ones from Kre-O (at least the ones from the USS Vengeance).</p>
  <p><em>Yours:</em></p>
  <p><a href="https://i.sstatic.net/EcFVf.png" rel="noreferrer"><img src="https://i.sstatic.net/EcFVf.png" alt="Long slope from OP's question" /></a></p>
  <p><em>LEGO:</em></p>
  <p><a href="https://i.sstatic.net/TZfAD.png" rel="noreferrer"><img src="https://i.sstatic.net/TZfAD.png" alt="LEGO Slope, Curved 6 x 1" /></a></p>
  <p><em>Kre-O:</em></p>
  <p><a href="https://i.sstatic.net/ajNdW.png" rel="noreferrer"><img src="https://i.sstatic.net/ajNdW.png" alt="Long slope from Kre-O USS Vengeance" /></a></p>
  <hr />
  <p>I did find another similar match and in the correct color: the <a href="https://www.groupon.com/deals/gg-ultimate-soldier-xd-f-18-fighter-jet-construction-set-2" rel="noreferrer">Ultimate Soldier XD F-18 Fighter Jet (Ad Blocker Warning)</a> as referenced in <a href="https://www.hisstank.com/forum/kre-o-g-i-joe-military-building-block-discussion/393257-post-up-your-kreo-building-block-displays-7.html" rel="noreferrer">this forum post</a>.</p>
  <p><a href="https://i.sstatic.net/7SNQo.png" rel="noreferrer"><img src="https://i.sstatic.net/7SNQo.png" alt="Tailfin from forum post" /></a></p>
  <p><a href="https://i.sstatic.net/nXqwE.png" rel="noreferrer"><img src="https://i.sstatic.net/nXqwE.png" alt="Tailfin on Ultimate Soldier XD F-18 Fighter Jet" /></a></p>
  <p><a href="https://i.sstatic.net/HtzTJ.png" rel="noreferrer"><img src="https://i.sstatic.net/HtzTJ.png" alt="Tailfin on Ultimate Soldier XD F-18 Fighter Jet" /></a></p>
  <hr />
  <p>Unfortunately again, the only details I can find about the brand (beyond the brick sets sold at Walmart and Amazon) seem to be about the figures, not building sets. There are a few <a href="http://figure-archive.net/toyline.aspx?toylineID=1432" rel="noreferrer">sites</a> <a href="https://www.figurerealm.com/actionfigure?action=seriesitemlist&amp;id=942" rel="noreferrer">archiving</a> <a href="https://www.collector-actionfigures.com/dash/universe/catalog_items/?category=2626" rel="noreferrer">these</a> figures if you're interested.</p>
  <p><a href="https://i.sstatic.net/vE4hS.png" rel="noreferrer"><img src="https://i.sstatic.net/vE4hS.png" alt="Ultimate Soldier sets at Amazon" /></a></p>
  <p><a href="https://i.sstatic.net/gtEDA.png" rel="noreferrer"><img src="https://i.sstatic.net/gtEDA.png" alt="Ultimate Soldier sets at Walmart" /></a></p>
  <hr />
  <p>I would have thought that the turbine piece would have been the easiest to identify, but I haven't come across anything close. Do you have more pieces that might be unique enough to give a clue?</p>
  <p><a href="https://i.sstatic.net/Q7AKx.png" rel="noreferrer"><img src="https://i.sstatic.net/Q7AKx.png" alt="Turbine from OP's question" /></a></p>
  <hr />
  <p>I'm curious to know if the molds from Kre-O's tailfin ended up being sold to someone else. That might explain both the nearly identical piece in the Ultimate Soldier sets (down to the injection sprue) and the obscurity of the set you're looking for.</p>
  <hr />
  <h1>Edit 1</h1>
  <p>According to the unsourced <a href="https://en.wikipedia.org/wiki/Ultimate_Soldier" rel="noreferrer">Wikipedia page for Ultimate Soldier</a>, the Ultimate Soldier brand of die-cast figures was reintroduced as a line of military-themed building toys in 2014.</p>
  <p><a href="https://forum.largescaleplanes.com/index.php?/topic/25970-so-what-happened-to-21st-century-toys-and-who-got-their-tooling/" rel="noreferrer">This forum thread</a> contains conjecture about the acquisition of the die-cast tooling by either JSI or All-Go. No mention of the building toys.</p>
  <p><a href="https://i.sstatic.net/WtOP6.png" rel="noreferrer"><img src="https://i.sstatic.net/WtOP6.png" alt="Forum post, transcriptionin quote below" /></a></p>
  <blockquote>
  <p>JSI bought some of the 1/18 tooling, there are a couple of company's sniffing around the 1/32 molds, but on my friends last trip to China(he's been back about a week) the 1/32 molds are either crated up of sitting inside and outside :rolleyes: the plant :lol: while other projects have taken over the factories.</p>
  <p>if they stay in weather to long they will be junk soon :huh:</p>
  </blockquote>
  <p><a href="https://i.sstatic.net/GuXke.png" rel="noreferrer"><img src="https://i.sstatic.net/GuXke.png" alt="Forum post, transcription in quote below" /></a></p>
  <blockquote>
  <p>For all intents and purposes, 21st Century is effectively gone. All-Go's attempt at resurrecting the line fell back into the mire it tried to spring from after reissuing the two 1/32 planes - the mistake they made there being twofold: they reissued paint schemes that had been done already (and at half the price) AND they no longer included a pilot figure. A lot of merchants dumped excess stock upon the failure of the planes to sell, and discounters like Tuesday Morning ended up with them.</p>
  <p>JSI seems to possess the bulk of the 1/18 molds and have reissued several of 21C's vehicles in that scale.</p>
  <p>As far as 1/32 goes, status remains unknown. Still a lot available on ebay, but obviously not at Wal-Mart prices. I have built several of the kits myself, and while plainly being more toy-like than your normal kit, they do clean up nice and if you get them at the right price are a bargain. I managed to snag a case of BF109F's for $20 a couple of years back.</p>
  </blockquote>
  <hr />
  <p>If the date provided by the Wikipedia page is to be believed, then there must be another explanation for the identical parts. I doubt that Hasbro would be selling good molds in 2014 for a line of toys they were still producing in 2017.</p>
  <p>So I checked who was actually making the toys for Hasbro. <a href="https://en.wikipedia.org/wiki/Kre-O" rel="noreferrer">The Kre-O line</a> is produced by the <a href="https://en.wikipedia.org/wiki/Oxford_(toy_company)" rel="noreferrer">Oxford</a> toy company in Korea. <a href="http://oxfordtoy.co.kr/index.asp" rel="noreferrer">Their website</a> is next to impossible to navigate in English, but with a little luck I came across this set with a familiar tailpiece.</p>
  <p><a href="https://i.sstatic.net/bg5bW.png" rel="noreferrer"><img src="https://i.sstatic.net/bg5bW.png" alt="Oxford Eastar Jet" /></a></p>
  <p><a href="https://i.sstatic.net/XKXZO.jpg" rel="noreferrer"><img src="https://i.sstatic.net/XKXZO.jpg" alt="Oxford Eastar Jet" /></a></p>
  <p>I couldn't find any closer matches on their website, but Wikipedia mentions that they made a line of military-themed sets. Using Google Translate, I searched <code>옥스포드 군사 장난감</code> (oxford military toy) and <a href="http://global.gmarket.co.kr/item?goodsCode=1509405941" rel="noreferrer">found some sets</a> that also contain pieces that appear to match the molds of your pieces.</p>
  <p><a href="https://i.sstatic.net/XNQd0.png" rel="noreferrer"><img src="https://i.sstatic.net/XNQd0.png" alt="Oxford CJ3651" /></a></p>
  <p>There's your slope again (apologies for the poor quality):</p>
  <p><a href="https://i.sstatic.net/N5Gt8.png" rel="noreferrer"><img src="https://i.sstatic.net/N5Gt8.png" alt="Sloped brick from Oxford CJ3651" /></a></p>
  <p><a href="https://i.sstatic.net/H35mE.png" rel="noreferrer"><img src="https://i.sstatic.net/H35mE.png" alt="Sloped brick from OP's question" /></a></p>
  <p>They even have the square-shaped negatives in the bottoms of some pieces:</p>
  <p><a href="https://i.sstatic.net/sIykl.png" rel="noreferrer"><img src="https://i.sstatic.net/sIykl.png" alt="Oxford Combat Plane" /></a></p>
  <p><a href="https://i.sstatic.net/TzNGh.jpg" rel="noreferrer"><img src="https://i.sstatic.net/TzNGh.jpg" alt="Oxford Combat Plane" /></a></p>
  <hr />
  <p>The Oxford military sets appear to be the source of the Ultimate Soldier sets still available on Amazon/Walmart. Just as they were rebranded &quot;Kre-O&quot; for Hasbro, it appears Oxford sets are/were rebranded &quot;Ultimate Modern Soldier&quot; for 21st Century Toys.</p>
  <p><em>Oxford:</em></p>
  <p><a href="https://i.sstatic.net/Mvmqm.png" rel="noreferrer"><img src="https://i.sstatic.net/Mvmqm.png" alt="Oxford OM33010" /></a></p>
  <p><em>Ultimate Soldier (Amazon):</em></p>
  <p><a href="https://i.sstatic.net/28e91.png" rel="noreferrer"><img src="https://i.sstatic.net/28e91.png" alt="Ultimate Soldier Attack Helicopter" /></a></p>
  <p>I'm still looking, but I'm nearly certain that your set was produced by Oxford. Either for one of their own lines or to be licensed by another company.</p>
  <hr />
  <h1>Edit 2</h1>
  <p>Completely by accident, I have stumbled on <a href="https://www.sluban.nl/en" rel="noreferrer">Sluban</a>.</p>
  <p><em>Turbine:</em></p>
  <p><a href="https://i.sstatic.net/9bOah.png" rel="noreferrer"><img src="https://i.sstatic.net/9bOah.png" alt="Sluban Stuntvliegtuig" /></a></p>
  <p><a href="https://i.sstatic.net/JGz4P.png" rel="noreferrer"><img src="https://i.sstatic.net/JGz4P.png" alt="Turbine from Sluban Stuntvliegtuig" /></a></p>
  <p><a href="https://i.sstatic.net/Q7AKx.png" rel="noreferrer"><img src="https://i.sstatic.net/Q7AKx.png" alt="Turbine from OP's question" /></a></p>
  <p><em>Tailfin:</em></p>
  <p><a href="https://i.sstatic.net/npvQE.png" rel="noreferrer"><img src="https://i.sstatic.net/npvQE.png" alt="Sluban Cargo Plane" /></a></p>
  <p><a href="https://i.sstatic.net/rSJWX.png" rel="noreferrer"><img src="https://i.sstatic.net/rSJWX.png" alt="Tailfin from Sluban Cargo Plane" /></a></p>
  <p><a href="https://i.sstatic.net/Jy2Dp.png" rel="noreferrer"><img src="https://i.sstatic.net/Jy2Dp.png" alt="Tailfin from OP's question" /></a></p>
  <p><a href="https://i.sstatic.net/3mydd.png" rel="noreferrer"><img src="https://i.sstatic.net/3mydd.png" alt="Sluban Straaljager" /></a></p>
  <p><em>Square recesses:</em></p>
  <p><a href="https://i.sstatic.net/YSdCk.png" rel="noreferrer"><img src="https://i.sstatic.net/YSdCk.png" alt="Sluban Tank" /></a></p>
  <p><a href="https://i.sstatic.net/CxiWZ.png" rel="noreferrer"><img src="https://i.sstatic.net/CxiWZ.png" alt="Square recesses from Sluban Tank" /></a></p>
  <p><a href="https://i.sstatic.net/IAilt.png" rel="noreferrer"><img src="https://i.sstatic.net/IAilt.png" alt="Square recesses from OP's question" /></a></p>
  <p><em>Cockpit:</em></p>
  <p><a href="https://i.sstatic.net/pvffL.png" rel="noreferrer"><img src="https://i.sstatic.net/pvffL.png" alt="Sluban Apachi Helicopter" /></a></p>
  <p><a href="https://i.sstatic.net/zwJiO.png" rel="noreferrer"><img src="https://i.sstatic.net/zwJiO.png" alt="Cockpit from Sluban Apachi Helicopter" /></a></p>
  <p><a href="https://i.sstatic.net/RJWmp.png" rel="noreferrer"><img src="https://i.sstatic.net/RJWmp.png" alt="Cockpit from OP's question" /></a></p>
  <p><a href="https://i.sstatic.net/lErA6.png" rel="noreferrer"><img src="https://i.sstatic.net/lErA6.png" alt="Sluban Land Forces II Helicopter" /></a></p>
  <p><a href="https://i.sstatic.net/Olo3P.png" rel="noreferrer"><img src="https://i.sstatic.net/Olo3P.png" alt="Cockpit from Sluban Land Forces II Helicopter" /></a></p>
  <p><em>Slope:</em></p>
  <p><a href="https://i.sstatic.net/lErA6.png" rel="noreferrer"><img src="https://i.sstatic.net/lErA6.png" alt="Sluban Land Forces II Helicopter" /></a></p>
  <p><a href="https://i.sstatic.net/MItlW.png" rel="noreferrer"><img src="https://i.sstatic.net/MItlW.png" alt="Sloped brick from Sluban Land Forces II Helicopter" /></a></p>
  <p><a href="https://i.sstatic.net/H35mE.png" rel="noreferrer"><img src="https://i.sstatic.net/H35mE.png" alt="Sloped brick from OP's question" /></a></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-08T20:09:16.333Z
Answers.LastActivityDate: 2021-05-09T04:24:33.820Z
Answers.LastEditDate: 2021-05-09T04:24:33.820Z
Answers.UserDisplayName: D M
Body: <p>This all came in a sealed pack. I can't seem to figure out which set it is - does anyone have any ideas? I'm sure there are more pieces to it.</p>
  <p><a href="https://i.sstatic.net/k6KYv.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/k6KYv.jpg" alt="enter image description here" /></a></p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-25T03:26:07.507Z
Comments.Text: Welcome to Bricks.SE. The set in the picture is a clone brand set, not a LEGO set, as there are no LEGO markings on the studs of the pieces. This will make it harder to identify, but there are some amazing set detectives on this forum who might be able to help.
Comments.UserDisplayName: Phil B.
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-25T13:20:24.520Z
Comments.Text: Looks like a plane model of some kind from the tail fin, cockpit bubble, and turbines (a big model, since there are at least 3 turbines; guessing there's a 4th somewhere). May need more pieces to determine the set, if you can find them.
Comments.UserDisplayName: TylerH
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-25T14:25:33.553Z
Comments.Text: The tail fin looks similar to the ones used on the [Kre-o Starscream](http://toybanditz.blogspot.com/2012/05/kre-o-starscream-plane-mode.html) and other models, which might help narrow it down a bit...
Comments.UserDisplayName: Zhaph - Ben Duguid
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-25T14:27:48.347Z
Comments.Text: @TylerH There have been are plenty of real-world tri jet planes. e.g. Boeing 727, Lockheed Tristar, DC-10, MD-11, Dassault Falcon, etc, etc - not to mention fictional designs of course..
Comments.UserDisplayName: alephzero
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-25T17:25:21.417Z
Comments.Text: Thank you my boys got about 5000 Legos handed down to them but no books so I'm trying to find some of the unique pieces to figure out some sets thank you now I know if it doesn't say Lego it's a different brand
Comments.UserDisplayName: Smv
Tags: <part-identification><set-identification><clone-brands>
Title: Need help identifying this non-Lego set - looks like a grey spaceship
UserDisplayName: Smv
ThreadText: # Need help identifying this non-Lego set - looks like a grey spaceship
  
  (Asked by: username_0 on 2020-08-25)
  
  This all came in a sealed pack. I can't seem to figure out which set it is - does anyone have any ideas? I'm sure there are more pieces to it.
  
  [![enter image description here](https://i.sstatic.net/k6KYv.jpg)](https://i.sstatic.net/k6KYv.jpg)
  
  **Tags:** part-identification, set-identification, clone-brands
  
  > **Comments:**
  > **username_1**: Welcome to Bricks.SE. The set in the picture is a clone brand set, not a LEGO set, as there are no LEGO markings on the studs of the pieces. This will make it harder to identify, but there are some amazing set detectives on this forum who might be able to help.  
  > **username_2**: Looks like a plane model of some kind from the tail fin, cockpit bubble, and turbines (a big model, since there are at least 3 turbines; guessing there's a 4th somewhere). May need more pieces to determine the set, if you can find them.  
  > **username_3**: The tail fin looks similar to the ones used on the [Kre-o Starscream](http://toybanditz.blogspot.com/2012/05/kre-o-starscream-plane-mode.html) and other models, which might help narrow it down a bit...  
  > **username_4**: @username_2 There have been are plenty of real-world tri jet planes. e.g. Boeing 727, Lockheed Tristar, DC-10, MD-11, Dassault Falcon, etc, etc - not to mention fictional designs of course..  
  > **username_0**: Thank you my boys got about 5000 Legos handed down to them but no books so I'm trying to find some of the unique pieces to figure out some sets thank you now I know if it doesn't say Lego it's a different brand  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_5 on 2021-05-08. Score: 9
  
  **Tl;dr**: most likely parts from [Sluban](https://www.sluban.nl/en) or [Oxford](http://oxfordtoy.co.kr/index.asp).
  
  ---
  
  # Original Post
  
  @username_3 is right that the tail fin looks like the one on the Kre-O Starscream:
  
  *Yours*:
  
  [![Tailfin from OP's question](https://i.sstatic.net/Jy2Dp.png)](https://i.sstatic.net/Jy2Dp.png)
  
  *Kre-O:*
  
  [![Tailfin from Kre-O Starscream](https://i.sstatic.net/CfLon.png)](https://i.sstatic.net/CfLon.png)
  
  ---
  
  I started looking for other Kre-O sets that use the piece. I found the [Toy & Game Instructions](https://consumercare.hasbro.com/en-us/instructions/kre-o?q=Kre+O&q=&hsb_doc_search_button=SEARCH) page which included sets with strikingly similar pieces.
  
  The [Kre-O Star Trek USS Vengeance - A4364 Instructions (PDF)](https://www.hasbro.com/common/documents/6d0a17b55056900b100f781b9c2c69e3/E8E7344650569047F5A337FF4E8E0497.pdf) cockpit is eight studs long while the cockpit in your photo looks to be about six studs long, but they have the same geometry.
  
  *Yours:*
  
  [![Cockpit from OP's question](https://i.sstatic.net/RJWmp.png)](https://i.sstatic.net/RJWmp.png)
  
  *Kre-O:*
  
  [![Cockpit from Kre-O USS Vengeance](https://i.sstatic.net/EHsQh.png)](https://i.sstatic.net/EHsQh.png)
  
  The [Kre-O Transformers Battle for Energon - 98812 (PDF)](https://www.hasbro.com/common/documents/6d0a17b55056900b100f781b9c2c69e3/1D0862565056900B10B3E6AD88A5C4FD.pdf) includes six-by-two stud sloped bricks that look like they could match the upside down brick in your photo.
  
  *Yours:*
  
  [![Sloped brick from OP's question](https://i.sstatic.net/H35mE.png)](https://i.sstatic.net/H35mE.png)
  
  *Kre-O:*
  
  [![Sloped brick from Kre-O Battle for Energon](https://i.sstatic.net/fq6bW.png)](https://i.sstatic.net/fq6bW.png)
  
  ---
  
  Unfortunately, it looks like the Kre-O inverted slopes (at least in [Kre-O Transformers Destruction Site Devestator - 36951 (PDF)](https://www.hasbro.com/common/documents/6d0a17b55056900b100f781b9c2c69e3/2315118F5056900B1042FAD0FA4C2DC5.pdf)) are closer to LEGO's inverted slopes than the ones in your photo.
  
  *Yours:*
  
  [![Inverted 2x3 slope from OP's question](https://i.sstatic.net/jWNKJ.png)](https://i.sstatic.net/jWNKJ.png)
  
  [![Inverted 2x3 slope from OP's question](https://i.sstatic.net/P4PvX.png)](https://i.sstatic.net/P4PvX.png)
  
  *Kre-O:*
  
  [![Inverted 2x3 slope from Kre-O USS Vengeance](https://i.sstatic.net/deW8I.png)](https://i.sstatic.net/deW8I.png)
  
  [![Inverted 2x3 slope from Kre-O Destruction Site Devestator](https://i.sstatic.net/DkWK8.png)](https://i.sstatic.net/DkWK8.png)
  
  *Yours:*
  
  [![Inverted 2x2 slope from OP's question](https://i.sstatic.net/Tbqe2.png)](https://i.sstatic.net/Tbqe2.png)
  
  [![Inverted 2x2 slope from OP's question](https://i.sstatic.net/j7TGf.png)](https://i.sstatic.net/j7TGf.png)
  
  *Kre-O:*
  
  [![Inverted 2x2 slope from Kre-O Destruction Site Devestator](https://i.sstatic.net/sCXWq.png)](https://i.sstatic.net/sCXWq.png)
  
  [![Inverted 2x2 slope from Kre-O Destruction Site Devestator](https://i.sstatic.net/Sim2R.png)](https://i.sstatic.net/Sim2R.png)
  
  It's hard to tell if your six-stud-long slopes are curved or not, but they look closer to [LEGO Slope, Curved 6 x 1](https://www.bricklink.com/v2/catalog/catalogitem.page?P=42022#T=C) than they do the ones from Kre-O (at least the ones from the USS Vengeance).
  
  *Yours:*
  
  [![Long slope from OP's question](https://i.sstatic.net/EcFVf.png)](https://i.sstatic.net/EcFVf.png)
  
  *LEGO:*
  
  [![LEGO Slope, Curved 6 x 1](https://i.sstatic.net/TZfAD.png)](https://i.sstatic.net/TZfAD.png)
  
  *Kre-O:*
  
  [![Long slope from Kre-O USS Vengeance](https://i.sstatic.net/ajNdW.png)](https://i.sstatic.net/ajNdW.png)
  
  ---
  
  I did find another similar match and in the correct color: the [Ultimate Soldier XD F-18 Fighter Jet (Ad Blocker Warning)](https://www.groupon.com/deals/gg-ultimate-soldier-xd-f-18-fighter-jet-construction-set-2) as referenced in [this forum post](https://www.hisstank.com/forum/kre-o-g-i-joe-military-building-block-discussion/393257-post-up-your-kreo-building-block-displays-7.html).
  
  [![Tailfin from forum post](https://i.sstatic.net/7SNQo.png)](https://i.sstatic.net/7SNQo.png)
  
  [![Tailfin on Ultimate Soldier XD F-18 Fighter Jet](https://i.sstatic.net/nXqwE.png)](https://i.sstatic.net/nXqwE.png)
  
  [![Tailfin on Ultimate Soldier XD F-18 Fighter Jet](https://i.sstatic.net/HtzTJ.png)](https://i.sstatic.net/HtzTJ.png)
  
  ---
  
  Unfortunately again, the only details I can find about the brand (beyond the brick sets sold at Walmart and Amazon) seem to be about the figures, not building sets. There are a few [sites](http://figure-archive.net/toyline.aspx?toylineID=1432) [archiving](https://www.figurerealm.com/actionfigure?action=seriesitemlist&id=942) [these](https://www.collector-actionfigures.com/dash/universe/catalog_items/?category=2626) figures if you're interested.
  
  [![Ultimate Soldier sets at Amazon](https://i.sstatic.net/vE4hS.png)](https://i.sstatic.net/vE4hS.png)
  
  [![Ultimate Soldier sets at Walmart](https://i.sstatic.net/gtEDA.png)](https://i.sstatic.net/gtEDA.png)
  
  ---
  
  I would have thought that the turbine piece would have been the easiest to identify, but I haven't come across anything close. Do you have more pieces that might be unique enough to give a clue?
  
  [![Turbine from OP's question](https://i.sstatic.net/Q7AKx.png)](https://i.sstatic.net/Q7AKx.png)
  
  ---
  
  I'm curious to know if the molds from Kre-O's tailfin ended up being sold to someone else. That might explain both the nearly identical piece in the Ultimate Soldier sets (down to the injection sprue) and the obscurity of the set you're looking for.
  
  ---
  
  # Edit 1
  
  According to the unsourced [Wikipedia page for Ultimate Soldier](https://en.wikipedia.org/wiki/Ultimate_Soldier), the Ultimate Soldier brand of die-cast figures was reintroduced as a line of military-themed building toys in 2014.
  
  [This forum thread](https://forum.largescaleplanes.com/index.php?/topic/25970-so-what-happened-to-21st-century-toys-and-who-got-their-tooling/) contains conjecture about the acquisition of the die-cast tooling by either JSI or All-Go. No mention of the building toys.
  
  [![Forum post, transcriptionin quote below](https://i.sstatic.net/WtOP6.png)](https://i.sstatic.net/WtOP6.png)
  
  > JSI bought some of the 1/18 tooling, there are a couple of company's sniffing around the 1/32 molds, but on my friends last trip to China(he's been back about a week) the 1/32 molds are either crated up of sitting inside and outside :rolleyes: the plant :lol: while other projects have taken over the factories.
  >
  > if they stay in weather to long they will be junk soon :huh:
  
  [![Forum post, transcription in quote below](https://i.sstatic.net/GuXke.png)](https://i.sstatic.net/GuXke.png)
  
  > For all intents and purposes, 21st Century is effectively gone. All-Go's attempt at resurrecting the line fell back into the mire it tried to spring from after reissuing the two 1/32 planes - the mistake they made there being twofold: they reissued paint schemes that had been done already (and at half the price) AND they no longer included a pilot figure. A lot of merchants dumped excess stock upon the failure of the planes to sell, and discounters like Tuesday Morning ended up with them.
  >
  > JSI seems to possess the bulk of the 1/18 molds and have reissued several of 21C's vehicles in that scale.
  >
  > As far as 1/32 goes, status remains unknown. Still a lot available on ebay, but obviously not at Wal-Mart prices. I have built several of the kits myself, and while plainly being more toy-like than your normal kit, they do clean up nice and if you get them at the right price are a bargain. I managed to snag a case of BF109F's for $20 a couple of years back.
  
  ---
  
  If the date provided by the Wikipedia page is to be believed, then there must be another explanation for the identical parts. I doubt that Hasbro would be selling good molds in 2014 for a line of toys they were still producing in 2017.
  
  So I checked who was actually making the toys for Hasbro. [The Kre-O line](https://en.wikipedia.org/wiki/Kre-O) is produced by the [Oxford](https://en.wikipedia.org/wiki/Oxford_(toy_company)) toy company in Korea. [Their website](http://oxfordtoy.co.kr/index.asp) is next to impossible to navigate in English, but with a little luck I came across this set with a familiar tailpiece.
  
  [![Oxford Eastar Jet](https://i.sstatic.net/bg5bW.png)](https://i.sstatic.net/bg5bW.png)
  
  [![Oxford Eastar Jet](https://i.sstatic.net/XKXZO.jpg)](https://i.sstatic.net/XKXZO.jpg)
  
  I couldn't find any closer matches on their website, but Wikipedia mentions that they made a line of military-themed sets. Using Google Translate, I searched `옥스포드 군사 장난감` (oxford military toy) and [found some sets](http://global.gmarket.co.kr/item?goodsCode=1509405941) that also contain pieces that appear to match the molds of your pieces.
  
  [![Oxford CJ3651](https://i.sstatic.net/XNQd0.png)](https://i.sstatic.net/XNQd0.png)
  
  There's your slope again (apologies for the poor quality):
  
  [![Sloped brick from Oxford CJ3651](https://i.sstatic.net/N5Gt8.png)](https://i.sstatic.net/N5Gt8.png)
  
  [![Sloped brick from OP's question](https://i.sstatic.net/H35mE.png)](https://i.sstatic.net/H35mE.png)
  
  They even have the square-shaped negatives in the bottoms of some pieces:
  
  [![Oxford Combat Plane](https://i.sstatic.net/sIykl.png)](https://i.sstatic.net/sIykl.png)
  
  [![Oxford Combat Plane](https://i.sstatic.net/TzNGh.jpg)](https://i.sstatic.net/TzNGh.jpg)
  
  ---
  
  The Oxford military sets appear to be the source of the Ultimate Soldier sets still available on Amazon/Walmart. Just as they were rebranded "Kre-O" for Hasbro, it appears Oxford sets are/were rebranded "Ultimate Modern Soldier" for 21st Century Toys.
  
  *Oxford:*
  
  [![Oxford OM33010](https://i.sstatic.net/Mvmqm.png)](https://i.sstatic.net/Mvmqm.png)
  
  *Ultimate Soldier (Amazon):*
  
  [![Ultimate Soldier Attack Helicopter](https://i.sstatic.net/28e91.png)](https://i.sstatic.net/28e91.png)
  
  I'm still looking, but I'm nearly certain that your set was produced by Oxford. Either for one of their own lines or to be licensed by another company.
  
  ---
  
  # Edit 2
  
  Completely by accident, I have stumbled on [Sluban](https://www.sluban.nl/en).
  
  *Turbine:*
  
  [![Sluban Stuntvliegtuig](https://i.sstatic.net/9bOah.png)](https://i.sstatic.net/9bOah.png)
  
  [![Turbine from Sluban Stuntvliegtuig](https://i.sstatic.net/JGz4P.png)](https://i.sstatic.net/JGz4P.png)
  
  [![Turbine from OP's question](https://i.sstatic.net/Q7AKx.png)](https://i.sstatic.net/Q7AKx.png)
  
  *Tailfin:*
  
  [![Sluban Cargo Plane](https://i.sstatic.net/npvQE.png)](https://i.sstatic.net/npvQE.png)
  
  [![Tailfin from Sluban Cargo Plane](https://i.sstatic.net/rSJWX.png)](https://i.sstatic.net/rSJWX.png)
  
  [![Tailfin from OP's question](https://i.sstatic.net/Jy2Dp.png)](https://i.sstatic.net/Jy2Dp.png)
  
  [![Sluban Straaljager](https://i.sstatic.net/3mydd.png)](https://i.sstatic.net/3mydd.png)
  
  *Square recesses:*
  
  [![Sluban Tank](https://i.sstatic.net/YSdCk.png)](https://i.sstatic.net/YSdCk.png)
  
  [![Square recesses from Sluban Tank](https://i.sstatic.net/CxiWZ.png)](https://i.sstatic.net/CxiWZ.png)
  
  [![Square recesses from OP's question](https://i.sstatic.net/IAilt.png)](https://i.sstatic.net/IAilt.png)
  
  *Cockpit:*
  
  [![Sluban Apachi Helicopter](https://i.sstatic.net/pvffL.png)](https://i.sstatic.net/pvffL.png)
  
  [![Cockpit from Sluban Apachi Helicopter](https://i.sstatic.net/zwJiO.png)](https://i.sstatic.net/zwJiO.png)
  
  [![Cockpit from OP's question](https://i.sstatic.net/RJWmp.png)](https://i.sstatic.net/RJWmp.png)
  
  [![Sluban Land Forces II Helicopter](https://i.sstatic.net/lErA6.png)](https://i.sstatic.net/lErA6.png)
  
  [![Cockpit from Sluban Land Forces II Helicopter](https://i.sstatic.net/Olo3P.png)](https://i.sstatic.net/Olo3P.png)
  
  *Slope:*
  
  [![Sluban Land Forces II Helicopter](https://i.sstatic.net/lErA6.png)](https://i.sstatic.net/lErA6.png)
  
  [![Sloped brick from Sluban Land Forces II Helicopter](https://i.sstatic.net/MItlW.png)](https://i.sstatic.net/MItlW.png)
  
  [![Sloped brick from OP's question](https://i.sstatic.net/H35mE.png)](https://i.sstatic.net/H35mE.png)
  
  
  ---
  
  