If you have a need or desire to have one of the fastest microSDXC cards available, there are only a handful of choices. The SD Association came up with the UHS-I Speed Class 3 rating to support 4K2K video recording, which requires a minimum of 30MB/s write speed. Kingston has released their first card with the latest UHS-I Speed Class 3 rating, featuring read speeds up to 90MB/s and write speeds up to 80MB/s.
The Kingston SDCA3/64GB card surpassed the rated read speed of 90MB/s with a CrystalDiskMark score of 93.75MB/s, but fell just shy of the rated write speed of 80MB/s with a score of 74.57MB/s on the test system; it still exceeds the requirements of the Speed Class 3 rating.
The SDCA3 microSDXC card is available in three sizes, 16GB, 32GB and 64GB both with and without the adapter. All of which includes a lifetime warranty if anything should happen to it. The 64GB version that Legit Reviews took a look at can be found online for $53.72 with free shipping.
Legit Bottom Line: The Kingston SDCA3/64GB is a very fast microSDXC card that will support 4K2K video recording. The clear choice is the Kingston SDCA3 if you want an extremely fast microSDXC card without spending a lot of money to record 4K Ultra HD video.