The Garmin Varia Radar Tail Light is a step up in rear light game. The world’s first cycling radar, Varia helps create a safer cycling environment by warning cyclists of vehicles approaching from behind up to 153 yards (140 meters). The radar tail light also warns approaching vehicles of a cyclist ahead, the light will alter its beam brightness and flashing mode in comparison to how close the following vehicle is getting. this gives the driver behind plenty of warning so there will be no excuses. Works seamlessly with compatible Edge cycling computers (Edge 1000, 820, 520). The compatible Edge computer can show multiple approaching vehicles and indicates the relative speed of approach and threat level warning you in advance if you have to take evasive action in order to stay safe. Overall this the next generation in taillights and will keep you seen at all the right times.