This rearview radar with tail light pairs with your Edge® bike computer or compatible smartphone to alert you of vehicles approaching from behind. Reliable rearview radar lets you ride like you know whats coming One radar. Multiple display options. Pair it with your compatible Garmin device, your phone or both The Variaapp has you covered if youre using your phone as a primary or backup display Its small, its easy to mount, and it works with just about any bike Maximum awareness Varia RTL515 rearview radar provides visual and audible alerts for vehicles approaching from behind up to 153 yards (140 meters) away. Multiple pairing options This radar works seamlessly with your Edge bike computer or compatible smartphone as well as select Garmin wearables or the optional radar display unit. Works with the Varia app This smartphone app helps you increase your awareness by providing graphicsplus tone and vibration alertsthat indicate the position and speed of approaching cars. Thi