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. Plate Hole Patterns - PDF Specs & Features Material: Powder Coated Marine Grade Aluminum Ball Size: 1.5" Rubber Ball Size Note:The "U" in the part number reflects product packaged in poly bag. The included plate is a universal mounting bracket with a selection of mounting hole locations. In certain applications additional holes may need to be drilled for proper fit with your electronic device. Weight:0.43 lbs. Videos Swing Arm Electronics Base - RAM Mount
