2.25" (D Size) Double Swing Arm with Swivel Socket Mount and 3.68" Diameter Base/2.25" Ball (AMPS). The RAM Mount RAM-VB-D-110-1U Double Swing Arm with Rotating Plate, allows you to twist and tilt the viewing angle of your laptop, tablet, UMPC, monitor, or any other connected electronic device, when mounted on your RAM Vehicle Mount. Taking the highly successful RAM Vehicle Mounts to the next level, this rotating swivel arm gives you even more viewing positions for your mounted electronic device while holding everything firmly in place.