RAM 4.75" Square Plate with VESA (4 X 75mm) (4 X 100mm) Hole Patterns and 1.5" Diameter Ball;

RAM Mounts 4.75 Square Inch VESA Base with Ball (Black)

The RAM Mounts RAM-246U marine-grade 4.75 inch square base (aluminum, pre-drilled with 75 mm and 100 mm holes) with a 1.5 inch diameter rubber ball. The RAM mounting base has the rubber ball positioned 0.88 inches from the center of one edge.