Elife Hot Sell Popular Weatherproof 4 Parking Sensors Car Backup Reverse Radar Kit Voice Alert Radar Detectors 4-sensor-system, double CPU and advanced chipset for enhanced coverage and detection (0-1.5m). A female voice will tell you the obstacle distance (0.4-2.0m) or warn you to "STOP" (0-2.0m), when the 4 sensors detect dangers. Help to prevent dangerous and costly collisions. Help to provide increased safety for passengers, pedestrians and family members who happen to be around the moving vehicle. Easy to install, the antenna can be attached to the inside of the rear bumper, not affecting the car external appearance.