... quality and long life time Item No: crown &pinion (mid) 99012340251 with ratio 17-28A: Features1) Material: Steel(20CrMo, 20CrMoTi, 42 ... built between us.Mobile:+86-13657687302Trademanager:cqyongyue crown &pinion (mid) 99012340251 with ratio 17-28