Piece of 1 Bumper PDC Reverse Parking Assist Sensor For Acura MDX 2017-2020 Features: Direct replacement, easy to install. The PDC system works by setting a PDC parking sensor on the front or rear bumpers of the car, detecting obstacles in front and rear, helping the driver to see the obstacles when parking. Accurate measure the distance of vehicle rear and nearest obstacle. It's convenient to park, this device protects the car body from scratches.