Quick Clamping Shaft Collar, System of Measurement Inch, Bore Type Round, Bore Diameter 5/16 in, Bore Thread Size Not Applicable, Collar Outside Diameter 1 1/2 in, Inside Height to Flat Not Applicable, Clearance Diameter Not Applicable, Collar Width 13/32 in, Collar Material Aluminum, Keyway Width Not Applicable, Collar Material Grade 6061, Keyway Depth Not Applicable, Thread Direction Not Applicable, Center to Lever Top 0.75 in, Collar Construction 1-Piece, Screw Material Stainless Steel WARNING: This product can expose you to chemicals including Ethylene thiourea, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov. -