A4 Stainless Steel Allen Bolts UNF

Also known as an Allen screw or Allen bolt, or simply a cap screw, socket head cap screws are a more modern alternative standard machine fastener to the standard hexagon headed bolt or setscrew, as found on much modern machinery. A hex key (otherwise known as an Allen key) is required to fit these fasteners. Conforming to ASME/ANSI B18.3, the contact surfaces of this screw or bolt are protected from external damage. Generally manufactured with a partial thread beyond a certain length and nominal diameter combination, but occasionally some stock may include a fully threaded shank.

A countersunk headed screw conforming with ASME/ANSI B18.3, requiring a hex key (otherwise known as an Allen key) to fit. The countersunk head is typically used in conjunction with a countersunk hole providing a flush, snag free fit. Generally manufactured with a full thread, though occasionally some stock may include a partially threaded shank.