WD Green 240GB M.2 2280 SATA 3D NAND SSD/Solid State Drive

While 2.5-inch SSDs use the SATA bus, which debuted in 2000 and was originally geared toward hard drives, and add-in cards use the PCIe bus, which is faster and has more bandwidth than SATA, M.2 SSDs can go either way, depending on the product. Additionally, some of the fastest and best SSDs use the NVMe interface, which was made for rapid storage devices.

So an M.2 SSD can be SATA-based, PCIe-based with NVMe support, or PCIe-based without NVMe support. An M.2 SSD with NVMe support offers up to five times more bandwidth than SATA M.2 models, bringing better performance in key tasks, such as file transfers, video or photo editing, transcoding, compression and decompression.

Most M.2 SSDs are 22 x 80mm (W x L), but can be shorter or longer. You can tell what size an M.2 SSD is by reading the four or five-digit number in its name or on its printed-circuit board (PCB). The first two numbers are its width, while the others are its length (example: M.2 Type-2280). Having a longer SSD means more space for NAND chips but not necessarily more storage space.