L. F. Hunter
This card continually unmounted in my S4. It was really painful, when I remounted the card I sometimes retrieved my files, sometimes not. I have to say, though, that a card test in my PC, using Crucial diagnostics, went fine. My gut feel is that the card overheats, and shuts down in the S4, although I have no proof of this. What I do know is that it didn't work for me, and many others (google it). Naturally, Amazon refunded me the purchase cost when I returned the card, gotta love Amazon.I now have a Samsung 64g card, and no problems so far. I like Sandisk, but there's a compatibility problem here with the S4.