Socket screws are commonly used in assemblies that do not provide sufficient clearance for a conventional wrench or socket.1/4"-28 Socket Head Cap Screw, Plain Steel, 2 in Length, 5 PK A hex key is required to tighten or loosen a socket screw..
. Machine screws are used in fastening nearly all types of hard materials.#10-24 x 1-1/2 in Phillips Flat Machine Screw, Plain Stainless Steel, 100 PK Commonly used with flat or lockwashers.