The RAM-D-101U, powder coated marine grade aluminum mount, consists of a double socket arm mount, two 2.5″ diameter round bases and the universal AMPS hole pattern. The rubber ball, socket technology dampens shock and vibration, as well as allows for almost infinite adjustment, perfect viewing angles. Ball Size: 2.25″ Rubber Ball Size Material: Powder Coated Marine Grade Aluminum Weight: 4.85 lbs. Note: The „U” in the part number reflects product packaged in poly bag. If you prefer a smaller double socket arm with two round bases, we prefer the (RAM-101U). RAM® double socket arms with their distinctive hour-glass shape are designed and recognized to provide the best possible performance for most any application.