It is rubber. It connects to one of the oil pump unions under the left carb cover, goes through a hole in the wall of the crankcase behind the oil pump, across behind the cylinders and connects to a barbed brass fitting on the right side of the crankcase which feeds the oil through the crankcase wall into the right rotary valve cover. The rubber is probably hard as a rock and a little heat or a knife will be needed to get it pulled/cut loose from the brass fitting on the right end. Try not to get garbage into the fitting as there is a pretty small orifice feeding the oil into the intake throat of the rotary valve cover.