Garmin GT21-TM Transom Mount Downvu TransducerGarmin GT21 TM Transom Mount DownVu Transducer is a compact, dual mode sonar solution designed for coastal and offshore anglers who want both traditional sonar and CHIRP ClearV scanning in one unit. Traditional sonar frequencies: 50 200 kHz with 600 W power; beamwidths 40 10; maximum depth up to 1,500 ft. CHIRP ClearV imaging: 260 kHz (245 275 kHz) and 455 kHz (445 465 kHz) with 500 W; beams 2. 0x51 @ 260 kHz and 1. 4x29 @ 455 kHz; maximum depth up to