Lowrance HST-DFSBL Transom Dual Frequency Transducer - 000-0106-77Lowrance HST DFSBL Transom Dual Frequency Transducer The dual frequency HST DFSBL includes a single ceramic element delivering both 50 kHz with a 29 beam width and 200 kHz with a 12 beam width. 50 kHz low frequency operation offers a maximum operational depth of 900 m (3000 ft), while 200 kHz high frequency provides higher resolution fish arches and bottom detail in shallower water. Depth Temperature One sensor does it all. Able to measure both depth