Socket head cap screws are a headed and externally threaded part designed for insertion through a close tolerance, internally tapped hole and mated with a nut. Tension on the socket cap screw is induced by rotation of the screw head. There is a hex socket in the head that accepts a hex wrench to tighten the socket cap screw. The point at the threaded end of the socket cap screw is machined flat so it will fit into a drilled hole.