I  was very happy with the performance of this SD card on my Samsung Galaxy s4. I never had an issue until yesterday. I went to look for a pic to show a friend and the SD card wasn't showing up in the gallery. I performed all the usual things we do when technology starts acting crazy. I took out the card, put it back in, restarted the phone, put the card in my card reader at home. NOTHING. It breaks my heart to say that I lost 2,500 pictures. (Yes, I take a lot of pictures, lol) Major sad face on this one. :(