Tension coil springs 1.Chair Tension Coil Spring, made of various steel; 2. RoHS compliance Coil Spring for automotive1.Material:carbon steel;spring steel;stainless steel,alloy steel.2.Wire Dia.:0.01mm-10mm5.Surface treatment:Zinc,Nickel,silver,golden,tin,powder coating.6.Applications: Automotive, medical device, electronics, toy,etc