M.2 SSD: B-Key/M-Key, NVMe vs SATA in one slot

B-Key, M-Key, B+M-Key

An M.2 slot has a notch (key) that determines which types of modules will physically fit into it. B-Key is usually associated with SATA or slower interfaces, M-Key — with full NVMe (PCIe), B+M-Key — a universal notch that physically accepts modules of both types, but does not guarantee electrical support for both protocols.

NVMe vs SATA — physically identical slot, different protocol

An M.2 NVMe module and an M.2 SATA module may look identical and fit into the same slot, but they use different data transfer protocols. If the motherboard supports only the SATA protocol in a specific slot, an NVMe drive either won't work or will be recognized with limited speed.

Module length

The most common lengths are 2242, 2260, 2280 (the first two digits are width in mm, the last two are length). A slot for a specific length has a corresponding standoff for the mounting screw.

Typical customer mistakes

• "M.2 SSD is always NVMe, so it's fast" — the M.2 form factor itself does not

determine the protocol; SATA also exists in M.2.

• "The slot physically accepts the module — therefore it's fully supported" — physical

compatibility does not guarantee protocol support by the board.

How to choose an M.2 SSD from us

Provide the exact laptop model — we will tell you which M.2 type (NVMe/SATA), which length, and whether there is an M.2 slot at all in this model.