This jams the end of the bolt, and provides the strength. Wedge Anchor, 1/4" Dia.Tightening the bolt results in a wedge being driven up against a sleeve., 2-1/4" L, Steel Zinc Plated, 100 PK.
M12-1.A hex key is required to tighten or loosen a socket screw. Socket screws are commonly used in assemblies that do not provide sufficient clearance for a conventional wrench or socket.