Dual Electronics 3.5 NavAtlas Auto Navigation Unit DualElect 3.5 NavAtlas Auto Navigation Unit. XNAV3550 GPS navigation system features the left and right turn signal LEDs on each side of the device. The XNAV 3550 brings you everything that a 3.5 inch navigation system would bring. You got your touch screen TFT LCD screen, integrated speakers, turn by turn voice guidance, rechargeable integrated battery, and an MP3 player. The maps are pre loaded onto the 1GB SD card, also loaded with millions of POI. The maps cover the entire USA.