• These narrow strips of polypropylene plastic welding rod are perfect for repairing or replacing those tiny slot tabs that you find on many bumper covers. Black pigment has been added to make a more invisible repair on black polypropylene parts. Each rod is 13/64" (5 mm) wide by 1/16" (1.6 mm) thick and 12" (30 cm) long and there are 30 rods in a pack.