M. 2. There are many pin definitions for the SSDs of ngff interface, which can be divided into a.b.c.. And M key according to the key bit score; 2230, 2242, 2260, 2280 and 22110 according to the size score; B + M key SATA data transmission protocol, B + M key PCIe x2 AHCI data transmission protocol, B + M key PCIe x2 nvme data transmission protocol, M key PCIe X4 AHCI data transmission protocol, M key PCIe X4 NVMe data transmission protocol; this product only supports M.2 NGFF solid-state disk of B+M key SATA transmission protocol in M.2 NGFF interface (solid-state disk has only 2 gaps, SATA protocol, and PCIe x2 NVMe and PCIe x2 with two gaps AHCI transmission protocol, please consult your official customer service of SSD, understand the transmission protocol of HDD, it is useless to buy the wrong one)!