M.2 for Hackers – Connectors
However, of course, it can cause confusion of the “it fits, but doesn’t work” kind. For instance, a B+M key SATA SSD will not work in some NVMe-only M-key sockets, and some proprietary standards like CNVi throw a wrench into the “any M.2 WiFi card will work with your laptop” concept.This is what I hate about M.2. If I plug something into a SATA port or USB port I know it's going to work. Why the hell would you bother making a keyed standard where matched-key products don't have to be compatible with one another?