Answers.Body: <p>jncraton and CreationEdge have both explained what the tubes are for and mentioned two advantages to not having them: nicer-looking clear parts, and connections that aren't aligned with the system stud grid. The main advantage to having them is the clutch power it adds: in a 2x2 brick such as the slope with no tube, each stud touches two walls, but with a tube each stud also touches the tube, so 50% more clutch. </p>
  
  <p>As I explained in <a href="https://bricks.stackexchange.com/questions/6698/what-are-the-differences-between-the-two-available-pizza-elements#comment8318_6699">this comment</a> regarding a pizza tile that had a variant element with a tube, the tube is a useful attachment point. The inside of the tube is a stud-hole so you can put a stud there, and this can be used to great effect with the right pieces. In the case of the pizza element, a minifig hand can be placed in the tube to hold the pizza centrally from underneath. Similarly bricks with tubes can be placed on half-stud offsets from other bricks using the tubes.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-11-12T14:44:31.217Z
Answers.LastActivityDate: 2015-11-12T14:44:31.217Z
Answers.UserDisplayName: Mr. Shiny and New 安宇
Answers.Body: <p>Parts with and without bottom tubes are nearly always interchangeable in normal building scenarios.</p>
  
  <p>However, there is definitely a functional difference. Not having bottom tubes generally does the following:</p>
  
  <ul>
  <li>Reduces clutch power. There's one less surface for the stud to produce friction against.</li>
  <li>Allows for lots of different connection points along the bottom edge rather than just at both ends. This can be useful in places where you aren't always working in whole numbers of modules. For example, here's one way that you could build a wall at 45 degrees to what you would normally build by exploiting 1x2 bricks without bottom tubes:</li>
  </ul>
  
  <p><a href="https://i.sstatic.net/lS01x.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/lS01x.jpg" alt="45 degree wall"></a></p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-11-16T22:05:17.373Z
Answers.Text: Accepting this answer just because it was the first and it has the most upvotes. All entries were great additions. Thanks to all participants!
Answers.UserDisplayName: Patrice Gahide
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-11-11T17:24:20.577Z
Answers.LastActivityDate: 2015-11-12T02:02:20.010Z
Answers.LastEditDate: 2015-11-12T02:02:20.010Z
Answers.UserDisplayName: jncraton
Body: <p>For instance:</p>
  
  <p><em>3040a - Slope 45° 2 x 1 - without Bottom Tube</em></p>
  
  <p>and</p>
  
  <p><em>3040b - Slope 45° 2 x 1</em></p>
  
  <p>Are both of these always interchangeable? If not, what are the cases where you would absolutely need no bottom tubes?</p>
  
Tags: <piece-information>
Title: Is there a functional difference between bricks w/ and w/o bottom tubes?
UserDisplayName: Patrice Gahide
ThreadText: # Is there a functional difference between bricks w/ and w/o bottom tubes?
  
  (Asked by: username_0 on 2015-11-11)
  
  For instance:
  
  *3040a - Slope 45° 2 x 1 - without Bottom Tube*
  
  and
  
  *3040b - Slope 45° 2 x 1*
  
  Are both of these always interchangeable? If not, what are the cases where you would absolutely need no bottom tubes?
  
  **Tags:** piece-information
  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_2 on 2015-11-11. Score: 10 | Accepted answer
  
  Parts with and without bottom tubes are nearly always interchangeable in normal building scenarios.
  
  However, there is definitely a functional difference. Not having bottom tubes generally does the following:
  
  * Reduces clutch power. There's one less surface for the stud to produce friction against.
  * Allows for lots of different connection points along the bottom edge rather than just at both ends. This can be useful in places where you aren't always working in whole numbers of modules. For example, here's one way that you could build a wall at 45 degrees to what you would normally build by exploiting 1x2 bricks without bottom tubes:
  
  [![45 degree wall](https://i.sstatic.net/lS01x.jpg)](https://i.sstatic.net/lS01x.jpg)
  
  > **Comments:**
  > **username_0**: Accepting this answer just because it was the first and it has the most upvotes. All entries were great additions. Thanks to all participants!  
  
  ---
  
  ### Answer by username_1 on 2015-11-12. Score: 4
  
  username_2 and CreationEdge have both explained what the tubes are for and mentioned two advantages to not having them: nicer-looking clear parts, and connections that aren't aligned with the system stud grid. The main advantage to having them is the clutch power it adds: in a 2x2 brick such as the slope with no tube, each stud touches two walls, but with a tube each stud also touches the tube, so 50% more clutch.
  
  As I explained in [this comment](https://bricks.stackexchange.com/questions/6698/what-are-the-differences-between-the-two-available-pizza-elements#comment8318_6699) regarding a pizza tile that had a variant element with a tube, the tube is a useful attachment point. The inside of the tube is a stud-hole so you can put a stud there, and this can be used to great effect with the right pieces. In the case of the pizza element, a minifig hand can be placed in the tube to hold the pizza centrally from underneath. Similarly bricks with tubes can be placed on half-stud offsets from other bricks using the tubes.
  
  
  ---
  
  