K-6640HERSH… Sold by the Each. Solid Brass Knob, 5/8 inch diameter and projects 5/8 inches. Attaches from the rear with a machine screw. Knobs are sold by the each. Brass knob may be antiqued with our brass darkening solution which is sold separate. You may also use our wood screw adapter, part number SCREWADAPTER-HERSH then knob can be attached with wood screw.