RAM Mount D Size 2.25" Ball Mount w/2 qty 3.68" Round Plates Short Length Double Socket Arm [RAM-D-101U-C]D Size 2. 25" Ball Mount with 2 qty 3. 68" Round Plates & Short Length Double Socket Arm The RAM D 101U consists of (2 qty) 3. 68" diameter round bases and SHORT length double socket arm. The 3. 68" diameter round bases have pre drilled holes, including two holes at 180 degrees and three holes at 120 degrees. Designed into the mount is a 2. 25" diameter patented rubber ball and socket system with adjustment points at both socket ends of the arm.