the compression spring is widely used for the automatic car,made with spring steel,passed ISO 9001:2000 and ROHS. top-quality products,customer's satisfaction,goodwill and continuous innovationmaterialCarbon steel,spring steel,stainless steel,alloy steel,oil tempered wireWire dia.0.3mm-8.0mmSurface treatmentEnvironmental protection zinc,nickel,become black,powder coating,cataphoresisor as your ...