Never used and tested (07/02/2014) with h2testw 1.4 today. Write rate is about 5.4 MB / s, and after about 15 GB came typo with code 21, after a further 4 GB again with error code 21 was carried out reading back the written data, however, without an error message (read rate of 17.2 MB / s) , Because of the write error with code 21 and the non-performance of the class specification part of this is now reclaimed and returned. I suspect that this card is a fake (Made in China) because Sandisk will be careful not to bring such cards in circulation, because that they would ruin their good name.