90303-ZVA-000 Hex (16mm) Nut - Overview. The 90303-ZVA-000 Hex (16mm) Nut is a critical component designed for use in Honda marine engine systems. This genuine OEM part serves the crucial function of securely fastening rigging and accessory hardware, ensuring mechanical stability and operational reliability within fuel, steering, or mounting systems. Manufactured to precise factory specifications, the Hex Nut acts as a key element in maintaining the integrity and durability of your marine engine