This O-ring seals a connection point within the hydraulic system of the host tractor. It sits between two mating faces, preventing fluid leakage under operating pressure. A degraded or hardened O-ring allows external seepage or internal cross-port leakage, which reduces system pressure and can introduce air into the circuit. The manufacturer machines this seal to the original cross-section and durometer, so it compresses to the correct fill ratio in the gland without extruding or rolling. On installation, ensure the sealing surfaces are clean and free of burrs; lubricate the O-ring with clean hydraulic fluid before assembly to prevent pinching.