Ensure your semi is Ready for the Road Ahead™ with fast and reactive rear air brakes, with the Bendix Remanufactured R-12® 4 psi Coreless Relay Valve. Due to its placement between the service reservoir and the rear air brakes, this replacement component is able to quickly release compressed air to actuate the air brakes. Constructed with a rugged metal body to endure extreme pressures and regular use. FleetPride is your First Click in Heavy Duty®.