In 2006 the SD Card Association defined a categorization according to the minimum writing speed called Class
|Minimum write rate (Mo/s)||2||4||6||10|
UHS (Ultra High Speed)
In addition to these classes, there are the UHS-I (Ultra High Speed I) specifications, whose RAM technologies used allow a higher theoretical average throughput, depending on the device using the card.
The second version of this UHS-II standard (November 2013) further increases the average theoretical throughput. adding a second row of pins to the card.
|SD Bus Interface||Hight Speed||UHS-I
|Minimum Sequential Write Speed||Speed Classes|
|Speed Class||UHS Speed Class||Video Speed Class|