Lowrance 000-12647-001 Hook-4 Sonar/GPS Mid/High/Downscan Fishfinder Lowrance 000-12647-001 Hook-4 Sonar/GPS Mid/High/Downscan Fishfinder CHIRP sonar plus downscan imaging the power of today's leading fish finder technologies combined to provide the best possible view beneath boat Downscan overlay Technology Overlays downscan imaging onto chirp sonar Advanced signal processing (asp) reduces need to manually adjust settings to see fish, structure & bottom detail more clearly Track back to review recorded sonar history including structure, transitions or fish targets, then pinpoint locations