I think this is the best market memory card at this time, the writing and reading speeds are so high that my hard pc does not follow, I used two, one for my Gopro 3+ hero (essential for 4k video) and one for my Sony Xperia Z2 which he filmed in 4K aissi can also counsel smartphone to use the internal memory as the sd card but could not keep this card no problem and the huge cash flow without problems. I suggest, another alternative is the Lexar 633X careful not to be confused with the 333x.