Phenolic resin; 0.750 in. Lg; hubs on boht ends; one 2.750 in. Dia., 0.100 in. Lg; 4 threaded holes, no.8-32 nc rh, spaced 90 degrees apart on a 2.250 in. Circle; one 1.280 in. Dia., 0.100 in. Lg; 4 threaded holes, no.8-32 nc rh, spaced 90 degrees apart on a 0.875 in. Circle