The RAM motorcycle handlebar base contains a 1" rubber ball designed to sit at right angles to the mounting rail. The double zinc coated metal u-bolts accommodate rails in diameter from 0.75" to 1.25" in diameter. The base also includes black cover caps to be placed over the exposed ends of the u-bolt. U-Bolt Dimensions: Accommodates rails from 0.75" to 1.25" in diameter. Material: Powder Coated Marine Grade Aluminium Ball Size: 1" Rubber Ball "B" Size