Shaft Collar System of Measurement Inch Bore Type Threaded Bore Diameter 1/2 in Bore Thread Size 1/2 In.-20 Collar Outside Diameter 1 1/8 in Inside Height to Flat Not Applicable Clearance Diameter 1.28 in Collar Width 13/32 in Collar Material Stainless Steel Keyway Width Not Applicable Collar Material Grade 303 Keyway Depth Not Applicable Thread Direction Left Hand Thread Center to Lever Top Not Applicable Collar Construction 1-Piece Screw Material Stainless Steel