Furuno FSV-24 Operator's Manual page 11

Audio function allows monitoring of echoes along user-selected area through
built-in loudspeaker.
Fish mark estimates fish speed.
Fish estimate feature compares volume of two fish schools.
Target lock automatically tracks fish school.
Net course mark shows probable drift of net against tide.
Event mark denotes important locations.
High power MOS FET transmitter for reliable operation.
Automatic screen degaussing
Comprehensive testing facility
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