The RAM motorcycle handlebar base contains a 1″ rubber ball designed to sit at right angles to the mounting rail. The zinc coated metal u-bolt accommodates rails in diameter from 0.5″ to 1.25″ in diameter. Included are black cover caps to be placed over the exposed ends of the u-bolt and a composite adapter that can narrow the rail to a minimum width of 0.5″. U-Bolt Dimensions: Accommodates rails from 0.5″ to 1.25″ in diameter. Material: Powder Coated Marine Grade Aluminum Ball Size: 1″ Rubber Ball „B” Size Note: Part number reflects product packaged in clear clam shell for store shelf display. This base is not rust proof. Click Here, to view the (RAM-B-231U), rust proof motorcycle handlebar base.