Automatic MA-WPSS-4M17 wireless parking sensor system assists drivers of trucks with trailers to identify hazards behind their vehicles when backing up. Dash-mounted system activates when reverse gear is engaged and alerts driver with both audible (active) and real-time visual (LED display) indicators to location of obstacles (zone discrimination) within four individual areas behind the vehicle, accurate to 12 in. Accommodates overhanging objects such as trailer hitches and extended bumpers. Waterproof sensors work in all weather conditions. Exchange function allows warning display unit to detect sensors installed on additional trailers. Mobile Awareness LLC, Solon, Ohio