The RAM-111BT universal base has a short post connected at right angles to a flat 6.25 x 2 inch rectangular base. The base has many 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 small post on the base is designed to connect to the RAM-109 series arms. Included on the end of the post is a tightening knob for use when installed on the compatible RAM-109 series arm. Product Features: 6.25 x 2 fishfinder and chartplotter plate adapter for RAM® marine swing arm mount Adapter plate compatible with select Garmin, Lowrance, Raymarine and Humminbird Fishfinders and GPS chartplotters Plate adapter works with CB radios, Ham radios and other gimbal brackets for radio mounting Backed by a lifetime warranty