Shaft Collar, System of Measurement Metric, Bore Type Round, Bore Diameter 7 mm, 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 Carbon Steel, Keyway Width Not Applicable, Collar Material Grade 1215, Keyway Depth Not Applicable, Thread Direction Not Applicable, Center to Lever Top Not Applicable, Collar Construction 1-Piece, Screw Material Alloy Steel This product contains a chemical that is regulated under California Proposition 65. Warning: This product contains a chemical known to the State of California to cause cancer. Warning: This product contains a chemical known to the State of California to cause birth defects or other reproductive harm. - Nickel (Metallic)