Zinc Plated Steel Shaft Collar, Set Screw Collar Style, Standard Dimension Type, 1/2 in Bore Dia./ OUTSIDE DIAMETER: 0.875 INCHES NOMINAL THICKNESS: 0.500 INCHES NOMINAL BORE DIAMETER: 0.5000 INCHES NOMINAL SECURING HOLE QUANTITY: 1 SCREW THREAD SERIES DESIGNATOR AND LOCATION: SINGLE HOLE UNF SECURING HOLE TYPE AND LOCATION: THREADED SINGLE HOLE NOMINAL THREAD SIZE AND LOCATION: 0.250 INCHES SINGLE HOLE MATERIAL: STEEL SURFACE TREATMENT: ZINC