Alerts You To Vehicles Approaching From BehindFirst radar system for bikes that warns of vehicles approaching from behind up to 150 yards (140 meters)Works independently and wirelessly integrates with compatible Edge® cycling computers¹Edge computer or Varia head unit can detect multiple vehicles and indicates the relative speed of approach and threat levelRear light unit brightens and flashes to notify approaching traffic of a cyclist aheadRadar BundleVaria radar display unit (RDU)Varia radar rear light (RTL 500)Stem mountVaria seat-post quarter-turn mountVaria universal seat-post quarter-turn mountmicroUSB cableManuals