Designed for SD devices that can capture Full HD 3D and 4K video as well as raw and burst photography the 256GB Extreme PRO UHS-I SDXC Memory Card from SanDisk has a capacity of 256GB is compatible with the UHS-I bus and features a speed class rating of V30 which guarantees minimum write speeds of 30 MBs. If your device does not support the V30 standard this card also supports the U3 standard which likewise guarantees minimum write speeds of 30 MBs. Read speeds are supported up to 170 MBs and write speeds max out at 90 MBs. A built-in write-protect switch helps to safeguard against the accidental erasure of card data.While this card has been designed for cameras that are UHS-I V30 U3 compatible it may be used in devices that do not support UHS-I V30 U3. However bear in mind that this card will then default to your devices speed class and bus rating such as UHS-I and U1 which supports minimum write speeds of 10 MBs or Class 10 which also supports minimum write speeds of 10 MBs.