Extension Spring, made of various material with different finish; Made in ISO/TS16949:2002 and ISO14001:2004 certified factory. Key Specifications/Special Features:Product Name: Extension SpringFeatures: Wire Diameter: 0.02 to 20mm;Raw material: stainless steel, carbon steel, spring steel, alloy spring steel, refractory steel, high temperature resisting alloy, corrosion-resistant alloy, brass, ...