Product Description 1. Available with customized materials and sizes 2. Extension spring can be used in automobiles, motorcycles, electrical appliances, Telecommunications and other domain. 3. All kinds of surface treatments are available: Polishing, zinc plating, nickel Plating, chrome plating 4. Mainly made of carbon spring steel, alloy spring steel, refractory steel and Stainless steel 5. OEM and ODM orders are welcome.