The RAP-B-111B-354-TRA1U consists of a Track Ball base, composite double socket arm and 6.25" x 2" rectangle plate. The 6.25" x 2" rectangle 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. The Track Ball base can connect to virtually any track system including the RAM Tough-Track. T-Bolt Dimensions: .48" x .95" Overall Height: 6" Plate Hole Patterns