90502-ZW7-U00 Plain (6mm) Washer - Overview. The 90502-ZW7-U00 Plain (6mm) Washer is a fundamental hardware component in Honda marine engine systems, specifically designed to provide reliable support within the rigging and accessory assemblies. Its primary function is to distribute the load evenly when fasteners are tightened, preventing damage to adjoining surfaces and maintaining structural integrity of the marine equipment. Engineered to meet factory specifications, this plain washer ensures