The RAM-B-101-C-231ZU consists of a zinc coated u-bolt base, LONGdouble socket arm and 2.5″ diameter round base that contains the universal AMPs hole pattern. Included in this package is hardware that will accommodate rails from 0.50″ to 1.25″ in diameter. The base includes black cover caps to be placed over the exposed ends of the u-bolt. The included composite rail adapter can narrow the rail to a minimum width of 0.5″. The mount is designed with a RAM 1″ diameter patented rubber ball and socket system that has adjustment points at both ends of the double socket arm; this allowing for almost infinite adjustment and perfect viewing angles. 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” SizeNote: The „U” in the part number reflects product packaged in poly bag.