Bolt Depot
Machine screws with no head for screwing all the way into threaded holes. Head Styles; Flat A countersunk head with a flat top. Abbreviated FH Oval A countersunk head with a rounded top. Abbreviated OH or OV. Pan A slightly rounded head with short vertical sides. Abbreviated PN. Truss An extra wide head with a rounded top. Round A domed head. Abbreviated RH. Hex A .