chain sprocket 1,25b-120b all type 2,high precision cnc tech 3,black oxide anti-corrosion ... ANSI C45 industrial machining hard teeth transmission chain sprocket 1, all made by advanced CNC lathe, pass ISO, ANSI,DIN quality ... nonstandard( according to the customer drawings) and standard(the metric system) sprockets 5, extensive use: machinery, metallurgy, mine, build, electron, port ...