... forming,with dense material and high strength,with surface spray coating treatment,with delicate lock.2,Piston:The material is 45#stell,with surface ... buffering in other word.3,Gear shaft:The material is 45#steel,with furface carburization treatment for high strength and wear ... -resistance. 4,Spring:Adopts quality spring steel,with less than 1mm shortening afer 300,000times squeezing.At door ...