... 3.Style: coil Detailed Product Description1) Air brake main spring for commercial brake spring and trucks2) Material: 60Si2MnA,55CrSi,oil tempered wire……3) Plastic ... 70% in brake spring. . Item nameBrake springsItem number153,151,Xiaojinlong,etcMaterial availablecarbon steel wire, stainless steel wire, spring steel, brass, aluminum, copper, alloy, etcSurface ...