A socket cap screw, also known as a socket head capscrew, socket screw, or Allen bolt, is a type of cap screw with a cylindrical head and hexagonal drive hole. ... Socket head capscrews are commonly used in assemblies that do not provide sufficient clearance for a conventional wrench or socket. Socket head cap screws are a special type of fastener. Socket head cap screws are typically used in machine parts, die fixturing, and clamping. Socket head cap screws with a drilled head features a hole drilled in the head to accept a wire thread as a safety feature.
Socket Head Cap Screws are heavy duty screws made from DFARS sourced alloy steel. Manufactured in the USA by Parker Fasteners, these strong externally threaded screws offer the highest strength for commercial fasteners, and are the ideal fastener where there is not sufficient space for wrenches or sockets.