PetSafe Drinkwell Replacement Carbon 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 activated carbon removes bad tastes and odors from the water making it more appealing to drink. Filters help extend the life of your fountain and pump. Compatible with Drinkwell Original, Platinum, Big Dog, Multi-Tier, Outdoor Dog, Mini, Everflow and Zen Pet Fountains PetSafe Drinkwell branded filters contain 50% more carbon than generic brands for better and longer-lasting filtration It is important to only use authorized PetSafe brand replacement filters in order to maintain product performance and warranty Fit securely in PetSafe Drinkwell fountains to more effectively filter water and debris To replace the filter, put the filter in the filter housing with the black side facing the front