I bought 5 of these microSD cards for use on my GoPro Black. I have unwrapped 3 so far. Of the 3, 2 cards are defective. Warning! It's very vicious: everything works for 2-3 days and it is after the plant map, making you lose all your data.
(I tried several combinations PC / card reader. Windows refuses formatting on the 2 cards is therefore a hardware problem).