Suitable for running, car driving, biking, or hiking. ? High accuracy GPS-based speedometer that is more accurate than the one in your car. ? Linear compass Shows your current direction of travel. A compass mode is also available. ? HUD mode Mirrors the numbers so you can place your phone on your car's dashboard and see the speed reflected in the front glass. You can check out this video to see how it works: http://youtu.be/rzda7CQ-ZAU ? Speed graph Displays a graph chart covering the last several minutes.