I bought two of the 32 GB Sandisk Ultra microSDHC cards, and both of them were unusable.The first one stopped accepting new data when I had put a bit less than one gig of data onto the card.  I couldn't add more files, and I couldn't reformat the card. If I tried to write a new file onto the card, the write operation seemed as if it worked, but the new data couldn't be read back successfully.  The files already on the card were still readable, though, so basically, the card had become a 1 GB ROM.  Fortunately, there was no sensitive personal information on the card, so I returned it to Amazon.The second one didn't fail the same way, but it was still unusable.  If I transferred a bunch of files and then read them back, most of the transferred files had data errors.  For example, a 3 minute music file might only be able to have it's first minute of music played back, then the bad data would stop the music player.  I ran a write/readback test and confirmed that there were data errors on nearly every block tested.  (I used Flash_Drive_Tester_v114.exe, which is a free download.)I ended up buying the equivalent Transcend productTranscend Information TS32GUSDC10 32GB micro SDHC10 Flash Memory - No Box or Adapterwhich has been performing flawlessly.  I have over half of the capacity in use, and I've never seen any sign of data loss or corruption.  For USB plug in flash drives, I've had good luck with SanDisk products, but my experience with the SanDisk microSDHC cards has been terrible.