SD Bus Interface Specification has been continuously increased over the years from High Speed (25MB/s) to 3rd Generation of Ultra High Speed UHS-III (624MB/s). Now the SDA offers SD Express which use the PCIe  Gen.4 Interface with NVMe Protocol to deliver (3940MB/s) data transfer rates between SD host devices and memory cards.


Any high speed cards can be used in UHS-I, UHS-II, UHS-III and SD Express host devices. Faster performance levels will only be attained when matching the card to the host device.

Therefore, devices supporting UHS-I perform the best with UHS-I memory cards. UHS-II devices also perform the best with UHS-II memory cards and UHS-III is the same. SD Express devices will perform best when using SD Express cards as well.