91331-PC9-003 O-RING (21.2X2.4) - Overview. The 91331-PC9-003 O-RING (21.2X2.4) is a vital sealing component used in Honda marine engine systems. This high-quality OEM O-ring is designed to provide a precise seal in fluid systems, helping to prevent leaks and maintain optimal system integrity. Manufactured to meet Honda's stringent factory specifications, this O-ring ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Genuine Honda OEM