91356-SD4-953 O-Ring (31.5x2.4) - Overview. The 91356-SD4-953 O-Ring (31.5X2.4) is a vital sealing component within Honda marine engine systems. Specifically designed to support the fuel and cooling systems, it helps maintain pressure and prevents fluid leaks, ensuring that your marine equipment operates efficiently and reliably. Manufactured to factory specifications, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Precise O-ri