Mission Rubber 300133 CK 33 Band-Seal Specialty Coupling, 3-Inch Cast-Iron to 3-Inch Copper Corrosion-resistant 300 Series stainless steel components Internal rubber sleeve reduces noise and vibration Easy to assemble, disassemble, and reuse Neoprene rubber sleeve conforms to ASTM C 564 Band-Seal Specialty Couplings conform to ASTM C 1460