The Meritor 4S/4M Rear ABS Valve Modulator is a highly reliable valve pack that is designed to provide superior levels of quality, performance and efficiency for your vehicle's rear axle system. This valve pack contains two ABS modulator valves and one service brake relay valve and can be easily attached to a frame cross-member. The ABS Valve Modulator is designed to provide superior braking performance and reliability and is an ideal choice for any vehicle that requires a reliable and efficient rear axle system. FleetPride is your First Click in Heavy Duty®.