Garmin 010-02376-00 Varia RTL515, Cycling Rearview Radar with Tail Light, Visual and Audible Alerts for Vehicles Up to 153 Yards Away

from Colin

Works well but make sure you have it high enough off your back tire, preferably attached to your seat or just underneath it, so the radar can increase its range.

from CAPTJAC

This is the top of the line radar that other than a helmet is my most prized safety equipment. Great for early morning and evening times to pick up cars not using Daytime Running Lights or headlights and when half brain dead 80 miles into a century on a hot afternoon. My old Varia Rearview Radar...

from Colin

Works well but make sure you have it high enough off your back tire, preferably attached to your seat or just underneath it, so the radar can increase its range.

from CAPTJAC

This is the top of the line radar that other than a helmet is my most prized safety equipment. Great for early morning and evening times to pick up cars not using Daytime Running Lights or headlights and when half brain dead 80 miles into a century on a hot afternoon. My old Varia Rearview Radar...

from Normand

Works well with no false negatives. Unit can be slow to react to light mode changes initiated from head unit (Edge 530).