Outfit your semi truck to be Ready for the Road Ahead with improved brake performance, with the OTR R-14 Type 4-Port Horizontal Relay Pressure Proportioning Valve. This replacement valve evenly distributes the brake pressure between the front and back wheels, providing enhanced control when slowing or stopping. Manufactured with an ultra-durable design to provide long-term reliability. FleetPride is your First Click in Heavy Duty .