This plastic transom mount transducer can be used in place of the dual frequency transducers included with many Garmin units.
The 500W 8-pin transducer has a maximum depth of 1,500 feet (457 m), an operating frequency of 50 to 200 kHz, a beam width of 40 to 10 degrees, and can be mounted on a 0 to 70 degree transom.
The transducer kit comes with installation instructions. Follow the instructions carefully to avoid damaging your boat.
The 6-pin transducer is preferable.
