... 1,25b-120b all type 2,high precision cnc tech 3,black oxide anti-corrosion 4,large ... Black Oxide Sprocket 1, all made by advanced CNC lathe, pass ISO, ANSI,DIN quality certification. high ... , smooth and steady, high strengthModel numberStandard or nonstandard (single duplex and triple)20A10-100, 40A10-100, 60A10-100 ... industrial machining hard teeth transmission chain drive black oxide sprocket wheel