Garmin Varia Rearview Radar Tail Light. For added peace of mind while riding on the road, the Garmin Varia Radar Tail Light is truly a game changer. The world's first cycling radar, the Varia helps create a safer cycling environment by warning cyclists of vehicles approaching from behind up to 153 yards 140 meters. Not only that, the tail light brightens and flashes to alert oncoming motorists of the cyclist on the road. The Varia Radar Tail Light can be used independently, but for added feedback the Varia wirelessly integrates with compatible Garmin Edge cycling computers. When the Varia is paired with an Edge computer, the cyclist will be alerted to multiple approaching vehicles with an indication of the relative speed of approach.