This is the lite version of speed mater which is free but displays adds.Speed Meter uses the GPS capabilities of your device to determine the speed and maximum speed obtained in km/h or mph with total distance covered. Total distance traveled is calculated in mph or km/h while the app remains open. The maximum speed and total distance traveled can be reset by pressing the R button. Please Note: Please ensure you allow location services when prompted for this app as this is required to obtain the speed. When driving please pay attention to the road, if you want to look at this app pull over and stop. The GPS function used to determine the speed may drain your battery faster then usual especially while using for extended periods of time, in this case please use a car charger or similar.