The RAM-B-238CH chrome plated aluminium plate has a 1.0" diameter rubber ball connected at right angles to a 1 1/4" x 2 1/2" diamond base. The plate has two pre-drilled holes positioned at either tip of the diamond plate. This part can be used as a mounting plate or to attach to any of the RAM plastic HOL holders with the industry standard AMPS hole pattern. Material: Powder Coated Marine Grade Aluminium Color: Chrome Finish Ball Size: 1 Inch Rubber Ball TIP: If you wish to use a Touratech holder most of them have clamps on the underside, remove them, but keep the screws and nuts and use them to attach a RAM diamond base, RAM-B-238 along the two holes in the centreline. TIP: The RAM-B-238 fits directly onto the back of the TomTom Rider 1 if you wish to use a RAM mount.