Product Details: The Airsource 1/8''-27 NPTF Air Sensing Switch is the perfect solution for detecting changes in air pressure and triggering ventilation systems to provide fresh air. This switch is designed to fit Peterbilt and Mack applications, being made from durable materials to ensure long-lasting performance. The switch is easy to install and designed to detect changes in air pressure and activate ventilation systems to provide fresh air. FleetPride is your First Click in Heavy Duty®.