Garmin Varia RVR315 Rearview RadarProvides visual and audible alerts for vehicles approaching from behind up to 140 metres away. Works seamlessly with your Edge bike computer or compatible smartphone as well as select Garmin wearables. The smartphone app helps you increase your awareness by providing graphics plus tone and vibration alerts to indicate the position and speed of approaching cars. When used with a compatible smartphone, Varia radar integrates with your favourite apps,