STEELMATE PTS400T Parking Assist System with 4 Wireless Rear Sensors 4 rear sensors for use in metal and plastic bumpers ECU connects to rear backup light 5 color LCD visual display that is mounted in front of vehicle and alerts detected objects with audible beeping and voice prompts Display changes color from green safe zone, to yellow, caution zone, to red alert zone, to flashing blue or white to prompt stop or park stage 18mm holesaw that matches sensor size