90201-ZW2-F01 Special (18Mm) Nut - Overview. The 90201-ZW2-F01 Special (18Mm) Nut is a critical component designed for the fastening system of Honda marine engine systems. This 18mm nut plays a vital role in securing various assemblies to maintain optimal operation and structural integrity. Manufactured to match strict Honda factory dimensions and tolerances, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Specially sized 18mm n