16721-ZZ5-003 Insulator - Overview. The 16721-ZZ5-003 Insulator is a crucial component within Honda marine engine systems. This specifically designed insulator supports the engine's fuel system by isolating vibrations and protecting other delicate components from heat, electrical currents, and mechanical wear. By minimizing vibration transfer and stress, it maintains reliable operation and longevity of the engine. Moreover, it is precision manufactured to match factory specifications, ensuring s