Shaft Collar System of Measurement Metric Bore Type Threaded Bore Diameter 4 mm Bore Thread Size M4x0.7 Collar Outside Diameter 16 mm Inside Height to Flat Not Applicable Clearance Diameter 20.8 mm Collar Width 9 mm Collar Material Carbon Steel Keyway Width Not Applicable Collar Material Grade 1215 Keyway Depth Not Applicable Thread Direction Right Hand Thread Center to Lever Top Not Applicable Collar Construction 1-Piece Screw Material Alloy Steel