Extension Spring, made of various material with different finish ... Name: Extension SpringFeatures: Wire Diameter: 0.02 to 20mm;Raw material: stainless steel, carbon steel, spring steel, alloy spring steel ... , and imitation gold-platedHigh-tech equipments: Advanced CNC spring machinery imported from Japan, Germany, Sweden, and TaiwanAdvanced ... molds, sports equipment and gifts, and more. Extension Spring