Adapt 4 in. clay piping to 3 in. cast iron, plastic, steel, copper or lead piping with this Fernco 4 in. x 3 in. PVC Flexible Coupling with Stainless-Steel Clamps. This flexible, underground-rated elastomeric PVC coupling features a 300-series stainless-steel clamp, which is rust- and corrosion-resistant, and features additional band slots for enhanced flexibility. Color: BLACK.