Molded black plastic. Designed to fit both aluminum and rubber rail molding. This unit attaches with screws through the vinyl or rope trim to prevent trim from slipping out. UV stable, chemical resistant and corrosion proof molded caps provide attractive and long lasting service. Butt splice for 1-1/4″ to 1-1/2″ rub rail, 2-1/4″ long. Sold per pair.