Shaft Coupler Body Coupling Size FC38 Outside Diameter 3 3/4 in Coupling Overall Length 6 5/16 in System of Measurement Inch Hub Material Carbon Steel Maximum Speed 1 750 RPM Keyway Depth 3/16 in Keyway Width 3/8 in Bore Diameter 1 5/8 in Shaft Locking Type Set Screw Bore Type Round Bore with Keyway Jaw Profile Straight Bore Tolerance +0.001/-0.000 in Hub Diameter 3 1/2 in