The RAM motorcycle handlebar base contains a 1" rubber ball designed to sit at right angles to the mounting rail. The rust proof metal u-bolt accommodates rails in diameter from 0.5" to 1" in diameter. The base also includes black cover caps to be placed over the exposed ends of the u-bolt. The RAP-319 shim is also supplied to cope with the 0.5" bars. U-Bolt: Accommodates rails from 0.5" to 1" in diameter. Powder coated stainless steel. Body Material: Powder Coated Marine Grade Aluminium Ball Size: 1 Inch Rubber Ball