Equip your semi truck to be Ready for the Road Ahead , with the Haldex 1/4" NPT 3-Way Pilot Valve, a key component that provides improved control over the flow of compressed air. Thanks to its robust design, this replacement piece is able to quickly actuate the flow of compressed air to auxiliary axle applications, cylinders, and more. Fashioned with an automated port that can be activated by applying pilot pressure. FleetPride is your First Click in Heavy Duty .