SX 4M2 has four M.2 sockets.
Below is a guide about the fastening mechanism of M.2 cards on SX 4M2:
General description
The locking mechanism has two parts
Standoff |  |
Screw |  |
SX 4M2 has multiple key-hole shaped openings for supporting different M.2 sizes.
Installation guide
Insert standoff in keyhole, groove down.
Push standoff to the narrow end of the keyhole.
Tip: If pushing the standoff in place is difficult, consider using a 4mm hex socket for pushing the standoff in place.
Install M.2 card in the M.2 slot and tighten the screw onto the standoff
