... -corrosion 4,large production, large stock Black Oxide Sprocket 1, all made by advanced CNC lathe, pass ... of high frequency quenching. 4, we also provide nonstandard( according to the customer drawings) and standard(the ... noise, smooth and steady, high strengthModel numberStandard or nonstandard (single duplex and triple)20A10-100, 40A10-100, ... teeth transmission chain drive black oxide sprocket wheel