91307-ZV5-821 O-Ring (1.5x15.5) - Overview. The 91307-ZV5-821 O-Ring (1.5x15.5) is a critical sealing component used within Honda marine engine systems. It functions to establish a watertight or airtight seal between various engine components, ensuring that fluids such as water and oil do not leak, thus maintaining the system's integrity and efficient operation. Manufactured to exact Honda factory specifications, this O-Ring guarantees a perfect fit and reliable performance essential for optimal