Brand New, Unopened SanDisk 256GB Extreme PRO SDXC UHS-I Memory Card - C10, U3, V30, 4K UHD, SD Card - SDSDXXD-256G-GN4IN Our most powerful SD UHS-I memory card saves you time transferring media with read speeds of up to 200MB/s (1) thanks to SanDisk QuickFlow technology (2). With shot speeds of up to 140MB/s (1) and UHS Speed Class 3 (U3) (4) recording, you can capture stunning, stutter-free 4K UHD video (3). | (1) Up to 200MB/s read speed. Designed with proprietary technology to reach speeds beyond UHS-I 104MB/s; requires compatible devices capable of reaching such speeds. Write speeds up to 140MB/s. Based on internal testing; performance may be lower depending on host device, interface, usage conditions and other factors. 1MB (megabyte) = 1,000,000 bytes. X = 150KB/sec. (2) SanDisk QuickFlow technology is only available for 64GB, 128GB, 256GB, 512GB and 1TB capacities. 1GB (gigabyte) = 1 billion bytes. 1TB (terabyte) = 1 trillion bytes. Actual user storage capacity less. (4) UHS Speed Class 3 designates a performance option designed to support 4K UHD video recording with a valid UHS host device. UHS Video Speed Class 30 (V30), sustained video capture rate of 30MB/s, designates a performance option designed to support real-time recording with UHS-enabled host devices. See the official website of the SD Association. (3) Full HD (1920x1080) and 4K UHD (3840 x 2160) video support may vary depending on host device, file attributes, and other factors). See the HD page on the SanDisk website.