This sealing washer is installed in the dispensing unit of a fertilizer spreader. It creates a seal between two stationary or moving components in the metering assembly, preventing fertilizer dust or granules from leaking past the joint. A degraded or missing washer allows material to bypass the intended flow path, leading to uneven application rates and potential corrosion of the mating surfaces. This original part is manufactured to the same thickness and material specification as the factory-installed seal, so it compresses to the correct height when the assembly is torqued.