94021-05020-0S Nut, Cap (5mm) - Overview. The 94021-05020-0S Nut, Cap (5mm) is a precise OEM Honda marine engine component designed to cap or cover specific 5mm threaded parts within Honda marine engine systems. This small but crucial hardware helps maintain the integrity of the engine's rigging and accessory connections, ensuring reliable operation and protection against environmental factors such as corrosion and mechanical wear. By snugly fitting over the threaded elements, it helps prevent c