M.2 PCI controllers

М.2

— the presence of at least one M.2 connector directly on the controller board.

This interface actually combines the capabilities of PCI Express 3.0, SATA3 and USB 3.0 (see the relevant paragraphs). Due to this, it can be used both for connecting drives (primarily SSD modules in a miniature form factor) and for expansion cards. The specific purpose and capabilities of the M.2 connector in different controller models may be different, these points should be clarified according to the manufacturer's documentation.