I put this in my Samsung Skyrocket phone.  Even though the phone says 32 GB  max, it still recognized and formatted the card.  Its great to have all of that space.However, any time i try to use the USB mass storage mode to transfer files, it errors out.  I thought it was the phone since it was larger than the max spec, but then I tried it in a USB card reader I had.  It still errored out trying the same files.  Finally, I had to put it in the adapter, and stick it in a card reader built into a laptop and transfer the files that way.I think the issue was that using the USB 2.0 the files were writing too fast and faulting out and with the laptop, transferring the files from the wireless network and then to the card, the transfer speed was slow enough that it was successful.  Took all night to get my stuff on the card though.I use it mostly for pics and video on my phone also, works great.  The phone seems to have no trouble accessing anything on the card and it seems  plenty fast for it even when recording high def video which i do a lot of for work.