The RAM-B-111U consists of a Mediumium double socket arm, 63mm diameter round base and 158 x 50mm rectangle base. The round base contains pre-drilled holes, Including the universal AMPS hole pattern. The rectangle base 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.