1.spring collar for wight plates 2.stainless 3.match different type olympic bars 4.OME service 1.collar2. Our factory is manufacturer can offer you much lower price2.can match all our products of weight plates and barbells3.can be used in Olympic bars (RB47, RB47T, RB66, RB66T, RB72, RB72T, RB86, RB86T )as the pictures show