... ISO, ANSI quality certification. high precision and good wear resistance. 2, surface treatment is black, galvanization, chroming and colored drawing. 3 ... : C45/A3, surface: chroming, heat treatment, standard: ISO,ANSINo.2 Machinery transmission sprocket:16A-18T, material:C45/A3, surface: heat ... surface: zinc plating, heat treatment, standard: ISO, ANSIOur stockProduction line 2.5M 20T bevel gear