Compost Pail Replacement Filters Keep odors contained in your kitchen compost pail. These replacement compost filters fit our Stainless Steel Odor-Free Compost Pail. Changing filters frequently ensure an odor-free environment - we highly recommend keeping extra filters on hand! Includes 2 sets (two 6.5" round and two 4.5" square filters). Charcoal filters keep unpleasant odors contained. Change filters at least every 4 to 6 months. Designed to fit our Stainless Steel Odor-Free Compost Pail. Helpful Hint: For best results, change your compost filters every 4 to 6 months, or sooner if odors are noticeable or you are frequently emptying your pail..