... 2.Material :aluminum, mild steel, stainless steel, chrome steel, cold rolled sheet, bearing steel, brass, copper, ... bronze, chrome copper, mold steel , teflon ,PVC, bakelite, nylon, delrin ... . 3.Surface treatment:hardening, carburizing, high frequency, anodizing, clear anodizing,black anodizing ,chrome plating, black oxide coating, nickel plating ...