Garmin Transducers - Single frequency transducers are used primarily for shallow water applications (normally under 3-500 feet). The Garmin Transducers frequency must match the sonar units frequency and the connectors must be the right Garmin Transducers connector for the sonar unit. Each Garmin Transducer has a list of the sonar units that the Garmin Transducer will fit. Different Garmin Transducers are provided for different applications.