This O-ring seals a connection within the brake system of the host tractor. It sits between two mating surfaces in the hydraulic or pneumatic brake circuit, preventing fluid or air leakage that would reduce braking pressure. A degraded or hardened O-ring allows loss of system pressure, leading to a spongy pedal feel or partial brake failure. The original part is molded to the same cross-section and durometer as the factory seal, which ensures it compresses correctly in the groove and maintains the designed clamping force. On reinstallation, inspect the sealing surfaces for burrs or debris before fitting the new ring.