This valve installs into the spring brake circuit of the air brake system, regulating air pressure to the spring brake chambers so the parking and emergency brakes apply and release properly. It is sold as a single unit for heavy-duty truck brake systems.Interchanges:110170EM40770FeaturesAir brake valveSold pack: 1 eachFunctions as a spring brake control valve in the air brake systemTech SpecsOEM Number: 110170Sell Pack: 1 Each