... : Brass, Bronze, Carton steel(low/medium/high carbon steel) Stainless steel, Aluminum alloy,Surface Treatment: ... patchCategory: 1. by components Bolts, Screw bolts/Studs, Nuts, Tapping screws, Wooden screws, Washers/Gaskets, ... Countersunk, Fillister, hexagon, Hexagon washer head, Hexagon socket button head and etc. 3. by type of drive inserts Phillilps, Slotted, Pillips/slotted combination, Cross ...