Equip your semi to be Ready for the Road Ahead , with the Dual Dynamics 120 psi Cross Fire Dual Tire Pressure Equalization System, a key piece that provides an equal distribution of tire pressure. By utilizing a sophisticated design, this replacement valve is able to seamlessly mount between dual tires to allow for a free flow of air to maintain equal pressure levels. Built with durable materials to tolerate extreme pressure levels. FleetPride is your First Click in Heavy Duty .