2 Replacement Filter sets for Endurance 1-gallon SS Compost Pail. Made of carbon coated nylon to help ensure an odor-free environment. Replace both filters every 4 to 6 months or sooner if you feel that odors are not contained enough or you are frequently emptying the contents. Remove filters before washing pail. Place round filter in first so it lays against dome lid, then square filter after.