The Garmin Varia RVR820 is a rear-facing radar that warns you about cars approaching from behind. It suits anyone who rides on open roads and would rather know what is coming than guess. The radar detects vehicles up to 140m back and displays their position and closing speed on your bike computer or phone, with an audible alert as they approach. Riders consistently describe it as the accessory that changed how they feel about traffic, particularly on rural roads where cars arrive fast and quietly. It also functions as a rear light, with a solid or flashing pattern that reacts to approaching vehicles. Key features Detects approaching vehicles up to 140m behind Visual and audible alerts on a paired head unit or phone Integrated rear light with vehicle-reactive modes Long battery life on a single charge Pairs with Garmin, Wahoo and other compatible head units Check compatibility with your specific head unit before buying. We can help confirm it.