Urethane Supply R10-04-03-BK 5003R10 Fiberflex Round Rod, 30'.Uni-Weld Rod (3/8"X1/16") - FiberFlex is Urethane Supply Company's "Universal" rod. It is not a true fusion weld, though. Instead, the FiberFlex is a hot-melt adhesive that is applied with a plastic welder. So, it is similar to a brazing process. It sticks great to polypropylene and TPO.