90301-ZW4-H01 Hex (5Mm) Nut - Overview. The 90301-ZW4-H01 Hex (5Mm) Nut is a critical fastening component designed for Honda marine engine systems. It plays an essential role in securely holding various assembly parts together, especially within the rigging and accessories system of Honda outboard engines. Its robust design ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. The nut is a 5mm hexagonal fastening device designed to fit s