We are a large scale spring manufacturer Our Extension Spring 1.Wire Dia.: Accurate free length of spring 2.Widely applied to industrial ... available.3.) Wire Dia. Range: Accurate free length of spring.4.) Material: carbon steel, chromium alloy steel, music wire, and ... steel, etc.5.) Finish: stress relieve, shot peen, plate, powder coat, passivate, electropolish, dye or paint, pake enamel, and plastic ...