Garmin 010-00765-00 GPSMap 431 Marine GPS Receiver: * The Garmin Marine GPS has an ultra-bright 4" diagonal QVGA display * 240 x 320 pixels, more than 800 nits of brightness * Preloaded with charts for more than 14,000 U.S. lakes and navigable rivers * Built-in high-sensitivity GPS receiver * High-speed processor for fast screen redraws and smooth panning * 2 NMEA 0183 I/O ports * Streamlined user interface makes it simple to select modes and features * Backlit keypad for easy operation in low light conditions * Single secure digital card slot for inland lakes vision cards, as well as saving waypoints, routes and tracks to a secure digital card * Optional inland lakes vision cards provide enhanced navigation features like auto guidance, satellite imagery, 3D mariner"s eye view and 3D fish eye view