Shaft Collar System of Measurement Inch Bore Type Round Bore Diameter 2 7/8 in Bore Thread Size Not Applicable Collar Outside Diameter 4 1/4 in Inside Height to Flat Not Applicable Clearance Diameter 4.5 in Collar Width 7/8 in Collar Material Aluminum Keyway Width Not Applicable Collar Material Grade 2024 Keyway Depth Not Applicable Thread Direction Not Applicable Center to Lever Top Not Applicable Collar Construction 1-Piece Screw Material Alloy Steel