Shaft Collar System of Measurement Inch Bore Type Round Bore Diameter 2 1/2 in Bore Thread Size Not Applicable Collar Outside Diameter 3 1/2 in Inside Height to Flat Not Applicable Collar Width 7/8 in Collar Material Carbon Steel Keyway Width Not Applicable Collar Material Grade 1045 Keyway Depth Not Applicable Thread Direction Not Applicable Center to Lever Top Not Applicable Collar Construction 1-Piece Screw Material Alloy Steel Collar Material Finish Zinc Plated