RAM Part RAM-137BU : The RAM-137BU, universal mounting plate, consists of a 1.5" diameter rubber ball, connected at right angles to a flat 3" x 11" rectangular plate. The plate contains different combinations of pre-drilled holes which will match up to many electronic devices and mounts, including Marine GPS, CB Radios, Ham Radios, Gimbal Brackets and more. This plate is a universal mounting bracket with a selection of mounting hole locations. In certain applications additional holes may need to be drilled for proper fit with your electronic device.