consists of a double socket arm, 3.68 diameter round base and 11 x 3 rectangular base. The round base contains pre-drilled holes, including two holes at 180 degrees and three holes at 120 degrees. 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. Compatible With: Garmin Fishfinders and GPS Chartplotters, Humminbird Fishfinders and GPS Chartplotters, Lowrance Fishfinders and GPS Chartplotters, Raymarine Fishfinders and GPS Chartplotters