Consists of delrin, type 1, cl 2 shaped into wheel 0.749 to 0.751 in. Dia, 0.355 thick, with centered smooth bore 0.251 to 0.252 in. Dia, lip 0.035 in. Thick, 0.865 to 0.885 in. Diameter on front rim; bore projects 0.030 in. Out the back with 0.302 to 0.322 in. Dia