The Garmin 76CSx GPS unit features unlimited memory, a super-sensitive receiver and a built-in compass and altimeter. SiRFstar III chipset provides rapid first fix and is sensitive enough to acquire signals in urban canyons and under dense foliage. Expandable memory has unlimited potential with the addition of larger microSD cards sold separately includes 128 MB card. Fast USB connectivity makes loading charts and maps quick and easy interface cable included. WAAS-enabled Wide Area Augmentation System receiver delivers 3-meter accuracy or better. Built-in electronic compass and barometric altimeter provide a steady bearing, altitude and atmospheric pressure trends. Precise barometric altimeter gives current altitude, ascent/descent rate and total ascent/descent. Trip computer calculates current and average speed, sunset and sunrise, trip time and distance. Forward-facing, backlighted control panel is easy to use in the dark innovative rocker toggle supplies quick, accurate panning and enter functions. Follow your route, marking up to 50 reversible routes and 1,000 waypoints find your way back with TracBack feature. Audible alarms for anchor drag, arrival, off-course, proximity waypoint and clock. Navigation instructions can be shared with repeaters, plotters and autopilots using NMEA protocols through the dedicated serial port. Comes with marine points and auto-route basemaps installed. Overstock.