RAM Mount Marine Electronics Mount Long Arm Gimbal Bracket [RAM-111U-D]The RAM 111U D consists of a 2. 5" diameter round base that contains the universal AMPs hole pattern, LONG LENGTH double socket arm and 6. 25" x 2" rectangle base. 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. The RAM 111U D is Compatible With: Garmin Fishfinders and GPS Chartplotters Humminbird