Shaft Collar System of Measurement Metric with Inch Bore Bore Type Round Bore Diameter 5/16 in Bore Thread Size Not Applicable Collar Outside Diameter 18 mm Inside Height to Flat Not Applicable Clearance Diameter 22.4 mm Collar Width 9 mm 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 2-Piece Screw Material Stainless Steel