Material steel.Usage furniture.Color steel color or black color. Detailed Product DescriptionOKE clip knot (spring parts),zigzag spring,sinuous spring,coil spring,sofa spring,seat spring,no sag spring,belong to sofa part OKE clip knot (sofa parts), zigzag spring,no sag spring,sinuous spring,coil spring,zig zag spring,sofa spring,seat spring,back spring belong to sofa part or sofa ...