I ordered 2 x 128GB micro-SD cards and was hesitant after reading several reviews that people said they’d received knockoff/fake cards. One of the criteria they list is that the cards weren’t as fast as SanDisk indicates. Part of testing a card means you have to test it on a device capable or reading and writing at the speeds they list the cards are capable of. If your computer can only read and write at 30mb/s then that’s as fast as the cards will operate. I think people think that magically if they put a fast read/write card into a device that the cards should read/write at those speeds not taking into account what the specs are of the SD reader/writer. There are definitely videos online that will teach you what to look for to determine fakes with packaging, printing on the packaging and cards etc. I’m not saying fake cards aren’t on the market, but you’re more likely to get fake cards on eBay or some shady site. None of the 14 x SD and micro-SD cards I’ve purchased on Amazon have been fake and I’ve used them over periods of years with no issues. If you’re concerned about fakes then educate yourself on how to identify fake packaging and printing and if you get a card in and you identify that before you tear open the packaging then Amazon is always the easiest place ever to return them for a refund.