RAM Mount Flat Surface Mount Short Arm w/Diamond Base [RAM-B-138U-A]RAM 1" Diameter Ball Flat Surface Mount with Short Double Socket Arm, 2. 5" Round Base & Diamond Base The RAM B 138U A consists of a 2. 5" diameter round base that contains the universal AMPs hole pattern, SHORT double socket arm and diamond base adapter. 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; this allowing for almost infinite adjustment and