Drinkwell Premium Replacement Carbon Filters. Designed specifically to fit a variety of Drinkwell pet water fountains, these high-quality filters feature a duo-density polyester pad that catches hair and debris, while the activated carbon helps make sure every refreshing sip of water your precious pet laps up tastes great and is free from foul tap-water tastes and odors. The drop-in filter is simple to install and should be replaced every two to four weeks to maintain optimum freshness and help prolong the life of the pump. Key Benefits: High-quality filters are designed exclusively for use in a variety of Drinkwell pet water fountains. Duo-density polyester pre-filter prevents hair, debris and sediment from entering the pump or water bowl. Activated carbon is distributed between six pockets to prevent settling and provide even filtration that removes bad tastes and odor from your furry friend?s water. Changing the filter regularly also reduces wear and tear on the water pump to help prolong its useful life. Available in convenient 3-count and 12-count packs; each filter provides two to four weeks of filtration.