M.2 NVMe SSD 256GB Samsung PM991, Interface: PCIe3.0 x4 / NVMe1.3, M2 Type 2242 form factor, Sequential Read: 2050 MB/s, Sequential Write: 1000 MB/s, Max Random 4k: Read / Write: 64K IOPS/220K IOPS, Samsung Phoenix controller, V-NAND TLC, Bulk