Rigid Shaft Coupling, 1 Piece Set Screw, Inch, Bore Dia. 5/8 in, Steel, Finish Black Oxide, Outside Dia. 1 1/4 in, Overall Length 2 in, With Keyway, Clearance Dia. 1.25 in, Screw Size 5/16 In. -18, Keyway Width 3/16 in, Max. Torque 469 in-lb, Max. RPM 1, 800 RPM