91303-ZV5-821 O-Ring (1.9X8.8) - Overview. The 91303-ZV5-821 O-Ring (1.9X8.8) is a crucial sealing component designed for Honda marine engine systems. Its role is to provide a watertight seal within the fuel and hydraulic systems, preventing leaks and ensuring the safe and efficient operation of your boat's engine. Crafted to exact factory specifications, this O-ring measures 1.9mm in thickness and 8.8mm in outer diameter, making it an essential part for maintaining system integrity and performa