The link to Garmin GST 43 Thru-Hull Transducer has been copied
The GST 43 is a thru-hull transducer that can read water speed and temperature. The transducer design is capable of being retrofitted to an existing Nexus 43 thru-hull transducer (TH43). Bundled with the GST 10, the GST 43 can connect directly to the NMEA 2000 network, and the information can be displayed on a compatible Garmin chartplotter or instrument display. Plastic construction will resist corrosion in marine environments.