My bad; I didn't read the reviews until after I bought a so-called "256GB Class 10" SD card for $13.99. I tried copying 32GB to the card. It never completed. I let it run overnight! I tried re-formating the card. It refused, and hung Apple Disk Utility. My brand new Olympus OM-D E-M1 Mark II refuses to even recognize the card, claiming "CARD ERROR." THEN I read the reviews -- tens of "one star" reviews, saying the same thing I experienced. But then, adding insult to injury, Amazon refused to post my negative review, saying it violated their "guidelines." I read their guidelines carefully, and saw nothing that was violated. Part of this refusal is that I have been banned from re-reviewing the same product. Luckily, Shamazon can't ban me from warning y'all! (Further insult to injury, a reply to the email I got from Shamazon, rejecting my review, came back as undelivered. They are not only blind to their customers, they are deaf, too!) Beware: Shamazon values its relationship with shady Chinese fraudsters more than it values its customers. I will never buy from Shamazon again! Remember, if it sounds too good to be true, it is!