The powder coated marine grade aluminum base contains a 1 inch diameter rubber ball connected at right angles to a 1.25 inch x 2.5 inch diamond base. The base has two holes 1.912 inch from center to center, positioned at both ends of the diamond base.
The (RAM-B-202U) RAM marine grade aluminum base contains a 1 inch diameter rubber ball connected to a flat 2.5 inch diameter base. This mount has pre-drilled holes, including the universal AMPS hole pattern.