Culligan Whole House O-Ring is designed to provide a reliable seal between the housing cap and canister, effectively preventing leaks in your water filtration system. This O-Ring is specifically compatible with Culligan models WH-HD100-O and WH-HD200-C, ensuring a fit and optimal performance. To install, simply remove the old O-Ring and clean the groove thoroughly with a clean cloth. Then, lubricate the new O-Ring with clean silicone grease and press it evenly into the groove using two fingers, making sure it sits completely level for a secure seal. This easy-to-follow process helps maintain the efficiency and longevity of your Culligan filtration system. Model Number: OR-250