Equip your semi to be Ready for the Road Ahead , with the Haldex AD-IP / AD-IS Air Dryer Purge Valve Assembly Kit, a crucial element that provides enhanced air dryer performance. Due to its numerous components, this replacement assembly is the ideal choice to release moisture that has been captured in the air dryer system. Constructed with top-quality materials to withstand harsh operating conditions. FleetPride is your First Click in Heavy Duty .