Specifications Rear sprocket: 34T/ 35T/ 36T/ 37T/ 38T/ 39T/ 40T/ 41T/ 42T/ 43T/ 44T/ 445T etc. Front sprocket: 13T/ 14T/ 15T/ 16T/ 17T etc 415, 420, 428, 428H, 520 etc Material A3# steel( SAE Q235) , 45# steel( SAE Q345B) ect. Surface finishing Sandblasting, Dull polish, galvanization, Polishing, Chrome plating, Painting, with the circle line in the surface or as your requirement. Heat treatment High frequency quenching and carburizating.