GT21-THPerfect for coastal and offshore fishermen who want traditional sonar and CHIRP ClearVü scanning sonar with a stainless steel stem, this thru-hull 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 ClearVü 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 frequencies of 50/200 kHz. It includes a built-in fast-response temperature sensor. For hull deadrises less than 25 degrees. GT21-TH includes an 8-pin transducer with stainless steel stem, fairing block, isolation plate and bushings, mounting hardware and installation instructions. Follow the instructions carefully to avoid damaging your boat.WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.