This is the Rostra 2501903BZP 4 Sensor Parking Sensor Kit.
Rear-mount Ultrasonic Automotive Parking Assist
BackZone Plus Functionality
The BackZone Plus is a revolutionary automotive reverse parking assist system developed by Rostra Precision Controls and designed to give every driver peace-of-mind while parking their vehicle in cramped quarters. The BackZone Plus provides both visual and audible alerts to the potential dangers of nearby obstacles through the use of an included buzzer built into a digital display that can be mounted on your sun visor or dashboard. When the vehicle is shifted into reverse, the system will automatically engage and output a single "beep" alerting the driver it has been activated. The system will further alert the driver to the presence of obstacles within each of its detection zones. From a pulsing beep to a steady tone, the BackZone Plus system works to keep drivers aware of their surroundings. The system goes silent again only when an obstacle is no longer in range of contacting the vehicle.
BackZone Plus Sensors
Included in every BackZone Plus ultrasonic parking assist system, you will find four bumper-mountable ultrasonic sensors with additional 6-degree and 12-degree angled bezels added to accommodate curved bumpers. Likewise, each kit includes four rubber sleeves to be used to reduce sensor vibration when mounting the ultrasonic sensors in steel bumpers. These sensors provide information to the main control module via the vehicle-length wiring harness, also included. The sensors included with each BackZone Plus arrive with a flat-black finish that can be painted to match the vehicle's exterior.