This is the ADATA Premier One 256GB microSDXC memory card, ADATA's flagship high-performance card line, built around a UHS-II interface for real professional-grade throughput rather than the UHS-I speeds most consumer cards top out at. It's rated U3 with read speeds up to 290MB/s and write speeds up to 260MB/s — several times faster than a typical UHS-I card — thanks to UHS-II's 16-pin dual-channel design, which remains backward compatible with older UHS-I devices and readers (just without reaching the higher UHS-II speeds on them). This level of sustained write performance is aimed at professional photographers and videographers shooting high-bitrate 4K/8K footage or high-speed burst photography who need the card itself to keep up with the camera. It carries SDMI compliance, ships with a full-size SD adapter, and is not compatible with SDHC-only devices or readers. ADATA backs the Premier One with a lifetime warranty.