Hi:I ordered two card and they arrived the next day, even faster than Prime. Unfortunatey, this 64gb MicroSD card is designed to only work with ex-fat. If you're an ex-fat fan and don't ever plan to change, this is the card for you. I've been able to take all of the previous 64gb MicroSD cards I've ordered, put them in an adapter and format them in my Windows 7 desktop. I'm a NTSF fan and find it to be much more stable in tablets.With other cards that aren't intentionally crippled, I can format the card to NTSF on Monday, ex-fat on Tuesday, Fat32 on Wednesday. It's ex-fat or the highway for SanDisk.You can use EaseUS Partition Master to format the card to Fat32 for devices such as cameras and mp3 players and many, many, many others that don't support ex-fat. That being said, you only get one shot. Once it's formatted into Fat32, attempting to format back to Exfat or NTSF hoses the card. I couldn't reformat to NTSF no matter what I tried. Once again, don't bother trying to format in your computer, ex-fat is the only choice.Any card that needs a special utility to format to anything other than ex-fat shouldn't be supported. Don't buy it! It's designed to fail.Shame on you Sandisk!Update 9/24/12:***************************I spoke with Sandisk technical support and they confirmed that Sandisk Ultra 64gb MicroSd cards are not compatible with Android 4.0 and above. This would be for Class 10, SanDisk Ultra 64 GB microSDXC Class 10 UHS-1 Memory Card 30MB/s with Adapter SDSDQUA-064G-U46A as well as SanDisk 64GB Mobile Ultra MicroSDXC Class 10 UHS-1 30MB/s Memory Card with SD Adapter (NEW VERSION) - Retail Packaging with Komputerbay SDXC USB Reader.I did not have any success formatting the class 10 card with EaseUS Partition Master. SanDisk recommended the free utility, HPUSBDISK.exe and I successfully downloaded it from Softpedia. I was  unable to format the card with NTSF but successfully converted one of the cards to Fat32 for a friend who wants to use it in a SanDisk mp3 player, that of course is not compatible with ex-fat.Acting on Sandisk advice I am returning the unopened class ten cards with the KomputerBay reader. I spoke with a patient and gracious tier-one tech support person and the party line seems be that consumers only use MicroSD cards in phones. I don't know what they're thinking: cameras, mp3 players, tablets, adapters and so on. Anyway it's a known issue.I can confirm that the class 6  64gb MicroSD card can be formatted in Windows7 back and forth to most any format so after returning four class 10 cards, I'm back to class six.It's still unconscionable to deliberately design these cards to be incompatible. I hope SanDisk will come up with a solution or recall the cards. Buyer beware.Update: 9/29/12**********************I received my two replacement class 6, 64gb MicroSD cards and it took less than five minutes to open the horrible packaging and to perform a quick format to NTSF. Done!I gave my friend the Class 10 64gb MicroSD card formatted into Fat32 by HPUSBDISK.EXE and he couldn't read it on his computer. As it turns out, the class 10 cards are not only incompatible with most devices bur also with most usb card readers.  Another trip across town.I can confirm that the IOGEAR SD/MicroSD/MMC Card Reader/Writer GFR204SD (Green/Gray) selling on Amazon for $6.99 works. So after countless hours of wasted effort, my friend has a card formatted to Fat32 that works with a SanDisk mp3 player.Once again, SanDisk has admitted that these cards are not compatible with Androd 4.0 or above, that being 100% of Android tablets and a majority of Android phones. These cards are intentionally crippled by design.To quote a friend:"Per the SDHC standard, the format is FAT32. SDXC (64 GB and larger) the spec calls for exFAT. Microsoft has limited the OS to only format larger cards as exFAT and will not allow FAT32. Also, seems they have found a way to also block NTFS. Thus far, very few Android devices can read exFAT because they refuse to pay M$ for licensing of the exFAT file system. "To all masochists out there--buy this card. To everyone else--unsafe at any speed.