The echo 551dv is a premier fishfinder with an all-in-one transducer that delivers both advanced HD-ID 77/200 kHz and Garmin DownVü scanned images simultaneously on a horizontally or vertically split screen. The images provide the clearest possible fish arch returns and nearly photographic bottom/structure details under the boat. With its bright, crisp 5-inch high-resolution VGA color display, the echo 551dv has Smooth Scaling which provides smooth transitions from shallow to deep water and back again. Narrow-to-wide viewing cone angles give you a big picture well beyond the sides of your boat - from shallow water down to 2300 feet maximum