Product Details: The Haldex Charging Plugged Auxiliary Reservoir Port Emergency Relay Valve is the perfect solution for maintaining and repairing your air brake system. This reliable and efficient valve is designed to control the parking and emergency brake functions on trailers. It has been rigorously tested to guarantee dependability and great efficiency. With its lightweight design of only 3 lbs, it is easy to install and use. It is the perfect choice for your air brake system maintenance and repair needs. FleetPride is your First Click in Heavy Duty®.