From https://www.micro-sd.net/micro-sd-a...:
Only two months after the release of App Perfomance Class 1 (A1), the SD Association has immediately raised the standard. It is now called 'App Perfomance Class 2' or A2. The standard raises the minimum limits for read operations to 2000 IOPS and write operations to 4000 IOPS. The minimum write rate remains at 10MB/s. The A2 standard thus increases the access rates for apps. A2 cards should thus feel significantly smoother than A1 cards.
