Mountable Shaft Collar, System of Measurement Inch, Bore Type Round, Bore Diameter 3/4 in, Bore Thread Size Not Applicable, Collar Outside Diameter 1 1/2 in, Inside Height to Flat Not Applicable, Clearance Diameter 1.81 in, Collar Width 1/2 in, Collar Material Stainless Steel, Keyway Width Not Applicable, Collar Material Grade 303, Keyway Depth Not Applicable, Thread Direction Not Applicable, Center to Lever Top Not Applicable, Collar Construction 1-Piece, Screw Material Stainless Steel WARNING: This product can expose you to chemicals including Nickel (Metallic), which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov. -