Product Details: The Hendrickson Trailer Height Control Valve is designed to help you maintain the proper ride height for your trailer. This valve allows you to adjust the air pressure in the trailer suspension system, allowing you to adjust the ride height to the optimal level for your specific trailer. This helps reduce drag and improve aerodynamics, as well as preventing the trailer from swaying or bouncing excessively. It also helps to prevent cargo from shifting or getting damaged during transport. FleetPride is your First Click in Heavy Duty®.