... Information About the SpringMaterialStainless steel, carbon steel, spring steel, alloy spring steel, refractory steel, brass, bronze, etc ... .Certification ISO9001:2008 ,ISO14001and ROHsEquipmentsAdvanced CNC computer spring machines with high precision and efficiencyTechnology Experienced engineers ... Free lengthThe overall length of a spring in the unloaded position.Total coilsThe total number of coils ...