After having my first ever failure of a SD card, a 32GB SanDisk Micro SD card that went from apparently fine to totally corrupted in a matter of minutes, and before I could salvage anything on it. With the refund from Amazon of the 32 GB card I purchased this 64GB Ultra card as the replacement for my phone.After having problems getting the full 64 GB seen as an individual 64 GB and not a partitioned into two 32 GB files on the card, and the secret is to NOT format the card in a computer, format the card IN THE PHONE, then via USB or WiFi you can add back all the content,It is seemingly working great, seems fast with no undo lag when taking burst mode photos and I just hope it will continue to do so. I am much more contentious about backing up though, with Android, Amazon and Google pretty much all your content can be saved online and reinstalled but it takes time and is a big hassle so just backing up to a computer works great for the next 'just in case' time.