Garmin 010-01569-00 echoMAP Chirp 55dv with transducer THE POWER OF SIMPLE - Easy-to-use, easy-to-install chartplotter/sonar combos with sunlight-readable, auto-dimming display and backlit keypad. Available in 4-inch, 5-inch square and 7- and 9-inch widescreen display sizes. CHIRP SONAR - CHIRP sends a continuous sweep of frequencies ranging from low to high, and interprets frequencies individually upon their return. With more information, CHIRP sonar is able to create crisper fish arches with better target separation. BUILT-IN MAPS AND CHARTS - Available with either U.S. BlueChart g2 charts, U.S. LakeV HD maps or Canada LakeV HD maps. BEST-IN-CLASS INTERNAL 5 Hz GPS - Internal 5 Hz GPS updates position and heading 5 times per second to make marking and returning accurately to waypoints easier. CLEAREST SCANNING SONAR ON THE WATER - The dv series comes with built-in 500 W (RMS) CHIRP traditional sonar and CHIRP DownV scanning sonar. The sv series offers all of the same features plus CHIRP SideV scanning sonar.