Garmin GT21-TMGarmin GT21 TM Perfect for coastal and offshore fishermen who want traditional sonar and CHIRP ClearV scanning sonar. this transom mount transducer consistently displays clear and crisp fish arches with superior target separation as well as clear definition of structure below the boat. The CHIRP ClearV element has a power rating of 500 W and operating frequencies of 260 455 kHz. The traditional sonar has a power rating of 600 W and operating