... 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 ... for you. About us:Dongguan City Yisen Precision Spring Co., Ltd. (Since 1998) is a high technology ...