A socket cap screw has a hexagonal recessed drive, usually with a cylindrical head, but can also be found with a rounded button head or a countersunk flat head. Socket cap screws can be torqued more tightly than other drives without stripping, and they are usually made from a high strength steel alloy.
Socket head cap screws are exceptionally strong and has a cylindrical head with a hexagon socket formed in the top. The screw is tightened with a normal allen wrench. In applications where the head of the screw will present a clearance problem, the hole to receive the screw can be enlarged at the top by counterboring. This operation allows the head of the fastener to be placed below the surface of the metal, out of the way of other objects. This makes up the bulk of the fastener applications stronger on fixtures. These screws are substantially stronger and more versatile than other screws. It has two advantages over the standard hexagon-headed bolt. First, the head takes up less space and second high quality socket head cap screws are more readily available than the high-quality hex bolts. These are often used in assemblies with counter bored holes.