Designed for microSD devices such as smartphones, drones, and action cameras that can capture Full HD and 4K video, as well as raw and burst photography, the 128GB Extreme UHS-I microSDXC Memory Card from SanDisk has a capacity of 128GB, is compatible with the UHS-I bus, and features a speed class rating of V30, which guarantees minimum write speeds of 30 MB/s. If your device does not support the V30 standard, this card also supports the U3 standard, which also guarantees minimum write speeds of 30 MB/s. Read speeds are supported up to 245 MB/s, and write speeds max out at 120 MB/s.