91303-800-000 O-Ring (16Mm) - Overview. The 91303-800-000 O-Ring (16Mm) is a vital sealing component in Honda marine engine systems, specifically designed to support fuel and engine systems by preventing leaks and preserving system integrity. This genuine OEM O-ring, measuring 16mm in diameter, plays a crucial role in ensuring seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Precisely sized 16mm O-ring that provides a secure and effective s