RAM Mount Double Ball Drill-Down Mount w/Diamond Plate Backer Plate [RAM-B-138U-C-INT3]Double Ball Drill Down Mount with Diamond Plate & Backer Plate This mount consists of a 2. 5" diameter round base that contains the universal AMPs hole pattern, a long double socket arm, a diamond base adapter, and a backer plate. The mount is designed with a 1 diameter patented rubber ball and socket system that has adjustment points at both ends of the double socket arm, allowing for almost infinite adjustment and perfect viewing angles. The hole