Socket button head cap screws are mostly used when the need for reducing the size of equipment arises. The critical characteristic feature of these screws is the wide load-bearing surface. A button head socket cap screw is a type of cap screw with a cylindrical head and hexagonal drive hole. A button head socket cap screw is most commonly driven with an Allen wrench or hex key. Most button socket cap screws feature clean heads with no stamping or marking for a nice clean finished look.