Boy do I feel burned with this SanDisk 64gb MicroSDXC card. Product 'worked' in my Motorola Photon 4G phone for about 6 weeks but then failed in the strangest way. The card has been loaded with roughly 47gb of data, some very personal, and it is now in a permanent READ ONLY mode. I can access what's on the card; read it, play it etc. but can no longer delete, erase, format or otherwise to anything to change the contents. This I have tried to do while memory card is in the phone or in a thumb drive adapter attached to my PC. All fails. So I am really stuck when it comes to warranty. If I want to submit for a replacement I'll have to send in the old card but since I cannot erase anything I would have to send it back with some pretty sensitive information...