Car LED Parking Sensor Kit with 4 Radar Accurate Digital Display of Obstacle Distance Alarm Parktronic Kit Suitable For Most Car ABOUT PARKING SENSOR Parking sensors are proximity sensors for road vehicles designed to alert the driver of obstacles while parking. These systems use either electromagnetic ultrasonic sensors. These systems feature ultrasonic proximity detectors to measure the distances to nearby objects via sensors located in the rear bumper fascias or visually minimized within adjacent grills or recees. The sensors emit acoustic pulses, with a control unit measuring the return interval of each reflected signal and calculating object distances. The system in turns warns the driver with acoustic tones, the frequency indicating object distance, with faster tones indicating closer proximity and a continuous tone indicating a minimal pre-defined distance. Rear sensors may be activated when reverse gear is selected and deactivated as soon as any other gear is selected. As an ultrasonic systems relies on the reflection of sound waves, the system may not detect flat objects or object insufficiently large to reflect sound e.g., a narrow pole or a longitudinal object pointed directly at the vehicle or near an object. Objects with flat surfaces angled from the vertical may deflect return sound waves away from the sensors, hindering detection. Also soft object with strong sound absorption may have weaker detection, e.g. wool or mo. FEATURES Condition: 100% Brand New Detecting Distance: 0.3~2.5m Alarm Distance: 0.3~1.5 Alarm Voice: >80dB at 10cm Supply voltage10.5V-15V(12V nominal) Current consumption200 mA max Working temperature20C-65C Storage temperature35C-85C The Diameter length 22 mm Note:please check the purchase options clearly, if you have any questions, please communicate with us first, we will handle it for you, please do not give bad feedback at will, thank you.