Review on Amplim 64GB V90 UHS-II SD SDXC Card: Lightning Speed, 300MB/S, Secure Digital Memory Storage for Pro Photographer and Videographer by Stephen Cooper

I am using this on a Sony A7Riii camera and it works there. I tested its performance using a Sony MRW-S1 SDXC II USB3 card reader and the CrystalMark tool in Windows 10 and compared it to a Sony SDXC II card and a SanDisk SDXC I card. Amplim's read speeds were pretty close to the advertised 285 MB/s. Speed - I got 271. But the write speed, which was not claimed, was a third of 91MB/s. That surprised me. The closest was a Sony card, the advertised read/write speed was 300/299 and it was outputting 289/257 - normal. The SanDisk card, which claims a read speed of 90MB/s (no write speed is listed), scored 99/50. Now, 91MB/s is still pretty darn fast and it's probably enough for 4K video and high-resolution photos, but the write speeds are what limit you when you're trying to copy a lot of data to the card at once (like when I fill camera buffer with 42 MP shots at 10 fps) and I would have preferred it to be faster. I think if I were to buy another card I would probably pay a (significant) additional fee to Sony. But if you watch your money, Amplim is fine. Edit December 22, 2017 I contacted Amplim to ask if the results I was seeing were as expected and they quickly replied that they were. The card complies with the SD Association V60 specification, which is more than sufficient for 4K videos. (The SD Association says it can support 8K video!) Sony's card doesn't claim a V specification. The Amplim card conforms to the new SD 5.0 specification.