1.Material:aluminum,brass.cooper. carbon steel. 2.Surface:zinc plating ,powdered,pas 3,SGS Certificate 4.OEM,ODM welcomed Compression Spring: 1.Material:steel,stainless steel.brass,aluminum,brass.cooper. carbon steel. 2.Surface:zinc plating ,powdered,pas 3.All our products are made by high-quality steels and first-class producing process Our Advantage; 1 FactoryEstablished in 2000,got SO 9001- ...