Shaft Collar System of Measurement Inch Bore Type Round Keyed Bore Diameter 1 1/2 in Bore Thread Size Not Applicable Collar Outside Diameter 2 3/8 in Inside Height to Flat Not Applicable Clearance Diameter 2.58 in Collar Width 9/16 in Collar Material Aluminum Keyway Width 3/8 in Collar Material Grade 2024 Keyway Depth 3/16 in Thread Direction Not Applicable Center to Lever Top Not Applicable Collar Construction 2-Piece Screw Material Alloy Steel Screw Material Finish Black Oxide