Satellite navigation, or which you know as sat nav deals, exceptional useful if you need the tool. Screen size is an important feature for GPS devices. A bigger screen map display provides a larger and more context where you are and what will happen. Most current GPS device is a touch screen, so you have to check the sensitivity of the screen before buying. The battery is an important thing to consider. Surely you want your GPS  have enough power to last a relatively long way. Most good GPS system is currently equipped with a car charger, with 4  to 7 hours of battery life. The last one is the price. Best GPS device is not too cheap or too expensive