The Humminbird XAP 9 20 Angled Puck Transducer is designed to mount to the inside of most fiberglass hulls with a deadrise greater than 15 degrees, and transmit the sonar signal downward through the hull itself. Your boat's hull must be of single-layer, fiberglass construction and be free of trapped air or voids in order for a puck transducer to operate correctly, so cored fiberglass, metal and wood will not work. This unit is meant to be glued to your inner hull with a slow-cure epoxy, which is included, and connects to your compatible Humminbird sonar or fish finder system via the included 15-foot cable.