1.High precision spring and high quality. 2.We can do OEM,ISO9001 3.We provide ... closed coil design and hooked ends. MaterialPiano wire, stainless steel, High Carbon Steel, Nickel Plated, Phosphor copper Bronze, Copper Bronze, Beryllium ... black or CustomizableApplicationsAerospace, Industrial, Medical applications, Automotive applications, Household appliances, Electronic, Toys, Hardware tool.