Although urethane bumpers are being made in gray and black, yellow bumpers are always urethane. If you see the symbols PUR, or RIM on the bumper, or you have determined that the plastic is indeed urethane, this is the rod you need. This polyurethane rod measures 20 ft. (6 m) long and 1/8th inch (3 mm) in diameter and works with Urethane Supply Company's Airless Plastic Welder.