Get your semi truck Ready for the Road Ahead™ with improved hydraulic fluid flow, with the Wabco 1/2" PTC Inversion Relay Valve. To help maintain a smooth and reliable braking experience, this replacement valve works to control application and release of brakes on the trailer when the truck is reversing. Constructed with a sophisticated design to help provide maximum safety on the road. FleetPride is your First Click in Heavy Duty®.