Prepare your semi to be Ready for the Road Ahead , with the MGM Brakes 3030 Standard Stroke Combo Spring Brake Chamber that provides enhanced brake safety. With a pressurized internal chamber, this replacement component applies the spring brakes as a safety measure once the air pressure falls below a certain point. Manufactured with a solid metal body to efficiently contain pressure and the energized spring brakes. FleetPride is your First Click in Heavy Duty .