Shaft Collar System of Measurement Inch Bore Type Round Bore Diameter 1 3/8 in Bore Thread Size Not Applicable Collar Outside Diameter 2 1/4 in Inside Height to Flat Not Applicable Clearance Diameter 2.31 in Collar Width 9/16 in Collar Material Stainless Steel Keyway Width Not Applicable Collar Material Grade 304 Keyway Depth Not Applicable Thread Direction Not Applicable Center to Lever Top Not Applicable Collar Construction 2-Piece Screw Thread Size 1/4 In.-28