90504-ZW4-H01 Washer (5mm) - Overview. The 90504-ZW4-H01 Washer (5mm) is a crucial component within Honda marine engine systems, serving as a 5mm standard washer designed to distribute the load of fasteners and prevent damage to connected marine equipment components. This washer supports the integrity of various rigging and control assemblies, ensuring reliable and durable connections vital for keeping Honda marine engines operating smoothly.. Key Features. The 90504-ZW4-H01 is an OEM genuine Ho