24-Count PetSafe Drinkwell Replacement Carbon Filters - (6 Packs with 4 Filters per Pack) 24-Count PetSafe Drinkwell Replacement Carbon Filters - (6 Packs with 4 Filters per Pack) Cylindrical filter with pull-tab for easy placement and removal Granulated carbon for extended filtration Duo-density polyester pad to capture debris Replace filters every 2 weeks for optimal fountain performance