The 1” Sleeve O-Ring is a critical rubber component used in Zurn Reduced Pressure Principle Backflow Preventers (models 375ST and 375XL). Designed to maintain a watertight seal within the sleeve section of the valve, it plays a key role in ensuring proper system performance and leak prevention. NSF-certified for use in potable water systems, it meets lead-free compliance standards, making it suitable for regulated applications.