Designed to work in conjunction with an existing flush mount, the pre-drilled and tapped gimbal mounts allow easy installation of Cannon, Fishlander, Big Jon, Scotty, Penn, and Walker downriggers. A 6" track can also be mounted in two different directions, parallel to the gunwale or parallel to the transom, on the top plate of the gimbal to give a wider range of use. When not in use, it can be removed to return the boat to its original condition Boats that are 30 feet and under are factory equipped with flush mounts that use a 30 degree 1 1/2" dia. x 10 1/2" long tube gimbal mount. This is the most popular size on the market today.