The Garmin Varia™ RTL515 Radar Tail Light pairs with your Edge® bike computer or compatible smartphone to alert you of vehicles approaching from behind. This tail light provides visual and audible alerts for vehicles approaching from behind up to 153 yards away. It works seamlessly with your Edge® bike computer or compatible smartphone as well as select Garmin wearables or the optional radar display unit. When used with a compatible smartphone, the Varia™ radar integrates with your favorite apps, such as Ride with GPS to overlay your maps with rearview radar alerts. Alert motorists to your presence as soon as possible with daylight visibility up to 1 mile by easily mounting this sleek, compact device on the seatpost of almost any road-use bicycle, its vertical design allows for better leg clearance and a perfectly comfortable ride. Enhance your riding experience with the Garmin Varia™ RTL515 Radar Tail Light!