This pack of 12 replacement charcoal filters are for the Drinkwell Avalon and Pagoda Ceramic Pet Water Fountains. Drinkwell Replacement Charcoal Filters keep your pet's water tasting clean and fresh. Each filter features a duo-density polyester pad that catches hair and debris, while the charcoal removes bad tastes and odors from the water making it more appealing to drink. Filters help extend the life of your fountain and pump and should be replaced every 2 to 4 weeks.