DO NOT PUT ANY IMPORTANT DATA IN IT. DO NOT USE IT AS A PERMANENT STORAGE TO ARCHIVE IMPORTANT FILES.It just failed after 1.5 months use -- i don't use it too much. Just put all my digital pictures (total: about 30GB) in it and carried in my wallet. I added some more pictures to the disk for a few time in November. Tonight, when I insert it into my laptop, Windows say cannot recognize the disk and said it must be formatted. I tried my MacBook Air and got the same. Neither Mac nor Windows can read it. I formatted it and started to copy the 30+GB pictures again. The copy broke in half way. Cancelled the copy, reinserted the disk and tried to resume the copy. Windows said the volumn is back and told me I must run chkdsk. I ran chkdsk and retried the copy. Still the same failure.I guess the disk has some problem and I don't bother recovering it, since it's not going to be reliable as I expected. Very disappointed. Thought SanDisk is a very good brand. I use SanDisk's CF card in my camera for years and it worked fine. I will fall back to use hard disk to backup my ditigal pictures.So it should be find to use this microSD disk to exchange some large file with friends. But don't put important data in it. Be prepard that it can fail at any time.