90303-ZW4-H00 Hex (12Mm) Nut - Overview. The 90303-ZW4-H00 Hex (12MM) Nut is an essential fastener component used within Honda marine engine systems. This 12mm hex nut ensures a secure and reliable threaded connection, contributing to the integrity of various assemblies in marine engines and boat equipment. By providing a dependable mounting solution, it helps keep the engine and rigging components operating smoothly and safely. Designed specifically for Honda marine applications, this nut integ