Socket head cap screws, or simply called ‘socket cap screws’ are used in machine parts and are especially common for removable panels and parts. Socket cap screws are the strongest 'socket' head type with a round cylindrical head and tightened with an Allen key (socket wrench) drive. Socket caps are the general term for Socket Head Cap screws, but loosely also refer toButton Head, andFlat Headscrews as well. Button Heads have a round head profile and are less likely to be hit or snagged, while Flat Heads are fully countersunk. We carry 12.9 Alloy steel (inBlack OxideorZinc platedsteel) and both18-8 (A2) and304 (A4)Stainless Steel options.