Shot speeds up to 90MB/s, transfer speeds up to 170MB/s [requires a compatible device capable of reaching such speeds, such as the SanDisk SD UHS I card reader (sold separately)]. Based on internal testing; Performance may be lower depending upon host device, interface, usage conditions and other factors 1MB=1,000,000 bytes; X = 150KB/sec Perfect for shooting 4K UHD video and sequential burst mode photography, Full HD (1920x1080) and 4K UHD (3840 x 2160) video support may vary based upon host device, file attributes and other factors Capture uninterrupted video with UHS Speed Class 3 (U3) and video Speed Class 30 (V30)(2) | (2) V30, sustained video capture rate of 30MB/s, & U3 designate a performance option designed to support real-time video recording w/ UHS enabled host devices.