This model is patible with various NMEA 2000 ponents inculuding Garmin's full lineup of NMEA 2000 marine sensors and autopilots. They are ready to go with a built-in satellite-enhanced worldwide basemap and Garmin's proven easy-to-use interface designed to help you navigate the open waters with ease.
Plus these waterproof units have a high-sensitivity internal GPS receiver so mariners will always know their position at sea. GPSMAP 421S Chartplotter/Fishfinder Combo - Without TransducerFeatures an ultra-bright 4" QVGA display along with an improved high-speed digital design for faster map drawing and panning speeds. Garmin GPSMAP 421s 4-Inch Waterproof Marine GPS and Chartplotter (Without Transducer) Details