Replacement O-ring seal for use with the Culligan WH-HD200-C. Ensures the seal of the water filtration system. The O-ring is used to seal the housing canister to the housing cap to prevent leaks. Replace your O-ring every third filter change or when there is damage to prevent leaks. Product Features: Used to help ensure the seal of the water filtration system Use with Culligan #WH-HD200-C (Ace #4697066) Made of Buna-N (Nitrile butadiene rubber)