Designed for SD devices that can capture Full HD, 3D, and 4K video, as well as raw and burst photography, the 64GB Professional 667x UHS-I SDXC Memory Card (2-Pack) from Lexar has a capacity of 64GB per card, which will allow you to shoot for extended periods of time while changing cards less frequently. It 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 100 MB/s, and if your device does not support U3, this card is compatible with the U1 and Class 10 standards, each of which guarantees minimum write speeds of 10 MB/s. To help safeguard your content, there is a built-in write protect switch.