This gasket seals the interface between the steering knuckle pin and the axle housing, preventing lubricant loss and ingress of contaminants. It sits in the recess machined into the knuckle pin bore, where it compresses under the retaining hardware to maintain a static seal. A degraded gasket allows grease leakage and dirt entry, which accelerates wear on the pin and bushing surfaces. As an original component, it is formed to the exact thickness and profile required to maintain the correct preload on the pin assembly without shimming.