Speed Marshal was developed in Europe for a flag called Code 60, in the USA there is one called Code 35. 60 is kph, 35 is mph. Our product enables the driver to acknowledge the flag and when activating the system it shows the driver what speed they are doing, and also externally it shows if they are above or below the speed. It also has two other safety features, standing start and breakdown warning systems. More details can be found on our dedicated website for this product www.speedmarshal.com