It's got your back while you ride ahead. Varia(TM) eRTL615 rearview radar for eBikes is our first battery-free radar. It plugs directly into your compatible eBike. It detects cars approaching from behind and provides audible and visible alerts when paired with your compatible Garmin smartwatch, bike computer or even your smartphone with the Varia(TM) app. This radar also has a bright tail light to make you more visible to motorists, adding peace of mind to every ride. And since you don't have to charge it between rides, that's one less thing to worry about.