The reversing radar is designed based on the principle that bats fly at high speed in the night without colliding with any obstacles. The probe is mounted on the rear bumper. According to different prices and brands, the probes are divided into two, three, four, six and eight, respectively. The probe radiates at a 45-degree angle and searches for the target up and down. Its biggest advantage is that it can explore obstacles that are lower than the bumper and the driver is difficult to see from the rear window, and alarm, such as flower beds, children playing in the back of the car. When the gear lever is engaged in the reverse gear, the reversing radar automatically starts working, and the ranging range is 0.3 to 2.5 meters, so it is very practical for the driver when parking. Features: Supply voltage：10.5V-15V(12V nominal) Current consumption：200 mA max Working temperature：20°C-65°C Storage temperature：35°C-85°C the Diameter length ： 22 mm Obstacle detection：from 150 cm from the bumper (post dia. 80 mm) Reliability over time：satisfies the strictest automotive standards Pack contains： 1 command module 4 ultrasonic sensors 1 power supply cable 1 hole borer 1 accessory kit 1 instruction manual IMPORTANT NOTES: This device has been designed as a driver aid and must not be considered infallible. Always manoeuvre vehicles with caution and using common sense. Manoeuvre your car slowly in the interest of your own safety and that of others. Always stop the vehicle when the hazard warning is activated, in order to take in account movement inertia. Periodically perform function checks on the sensors and ensure that they are clean at all times. In the event of rain, snow or ice, the sensors may be subject to a temporary drop in sensitivity of approximately 20%. Drive with even grater caution until evaporation is complete. Notes: Please allow 1-3mm（cm） differs due to manual measurement. Due to the different monitor and lights, the pictures may not show the actual color of the item. Thanks for your understanding.