Steel; 3.624 in. Od large end; 2.631 in. Od small end; 1.245 in. Id w/keyway 0.250 in. W by 0.125 in. Deep; 0.507 in. Thk flange; one unthd hole through flange 0.250 in. Dia; counterbored on back side; one thd hole through od of flange to bore over top of keyway; 5/16-18 unc-2b rh thd