micro SD cards Speed Speed class rating How Different Are U1 Vs U3 SD Memory Cards & CF Vs XQD Cards?. u3 faster than u1. Capacity SDSC (SD) 1 MB to 2 GB,some 4 GB were made. SDHC <2 GB to 32 GB. SDXC <32 GB to 2 TB. 16 GB cheap ones for installation UHS-I U1 KINGSTON 16GB microSDHC Class10 UHS-I. 128 GB for music UHS-I U3 Samsung EVO Plus microSDXC 128GB Class 10 UHS-I.