90304-ZV4-000 Hex (6mm) Nut - Overview. The 90304-ZV4-000 Hex (6mm) Nut is a critical fastening component used in Honda marine engine systems. This hex nut supports various engine assemblies by providing secure and reliable mounting points, essential for maintaining consistent mechanical integrity and performance. Designed to fit precisely within the Honda marine rigging and accessory systems, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. K