Quick Clamping Shaft Collar, System of Measurement Metric, Bore Type Round, Bore Diameter 21 mm, Bore Thread Size Not Applicable, Collar Outside Diameter 42 mm, Inside Height to Flat Not Applicable, Collar Width 15 mm, Collar Material Stainless Steel, Keyway Width Not Applicable, Collar Material Grade 303, Keyway Depth Not Applicable, Center to Lever Top 38.8 mm, Collar Construction 2-Piece, Screw Material Stainless Steel, Resistance Properties Corrosion Resistant, Screw Seating Torque 9.6 N-m