With a highly sensitive GPS receiver inside, the Garmin GPSMAP 640 helps you to smoothly navigate in the water. This marine chart plotter is also an on-road navigator that guides you with voice-prompted and turn-by-turn directions. This Garmin GPS receiver features a 5.2-inch WVGA color touchscreen that is easy to view and operate. You can store additional maps on this Garmin GPS receiver, thanks to the SD expansion card slot. Sporting a sleek and portable design, you can always carry the Garmin GPSMAP 640 wherever you go. The Garmin GPSMAP 640 marine chart plotter is preloaded with BlueChart g2 marine data as well as coastal and detailed road maps, to help you reach your destination with ease.