sprocket 1,25b-120b all type 2,high precision cnc tech 3,black oxide anti-corrosion 4,large ... 1, all made by advanced CNC lathe, pass ISO, ANSI,DIN quality certification. high precision and good wear resistance. 2, ... treatmentBlacking, galvanization, chroming, electrophoresis, color painting, or customer requirementPerformanceHigh precision, high wear resistance, low noise, smooth and steady, high ...