This selective on/off feature is only available with a sonar that can use the BroadView transducer, like the TriFinder® 3Beam. With Advanced Fish I.D.(tm) on, TargetTrack(tm) will digitally display the depth AND the location of each sonar target on the screen. For example, a fish symbol with "L29" above it means the target is in the left sonar beam at 29 feet. "R11" is a fish in the right beam at 11 feet. A depth display without "L" or "R" means the target is in the center sonar beam. Because the TriFinder® 3Beam sonar covers a much wider underwater area - up to 150 degrees - TargetTrack(tm) aids anglers in making more accurate casts at specific fish targets.