"The RAM-VP-SW1-1218-2461 consists of a 18"" lower female Tele-Pole, 12"" upper male Tele-Pole, double swing arm and 3.625"" square base that contains the VESA hole pattern. The lower female Tele-Pole will attach to all RAM vehicles bases that do not contain a welded female Tele-Pole. The height of the Tele-Poles, combinded, can easily be adjusted by turning the knob at the top of the post. Once the knob has been tightened, the Tele-Pole becomes a rigid support for connecting devices or cradles. The double swing arm allows you to twist and tilt the viewing angle of your connected electronic device, when mounted on your RAM Vehicle Mount. The rotating swivel arm gives you even more viewing positions for your mounted electronic device while holding everything firmly in place. The length of the double swing arm is 12"". The 3.625"" square base includes a 75mm X 75mm VESA hole pattern with 1.5"" rubber ball positioned 0.88"" from the center of one edge."