... Time:10 Years Buying tipsThe most popular, the low speed, small power, can choose the A3steel Carburizing, quenching,tempering, HRC50 ~ ... 60 have impact load, Teeth more than 25, can choose ... fire, 160 ~ 200HB requirements wear resisting, no violent impact, can chose 45 #steel -- sprocket -- Yamaha:AG100,DT100,DT125, ...