Coido - Car Parking Reverse Sensors 4 sensor system Description 1)4 sensor system. double CPU and advanced chipset for enhanced coverage and detection(0-2.5m). 2)With digital colored LED display(number and light). 3)Helps to prevent car from collision. 4)Helps to provide increased safety of passangers, pedestrians who happen to be around the moving vehivle. 5)Detect small children and low walls as well.