The PetSafe Drinkwell 360 Plastic Pet Fountain Replacement Foam Filters traps any large particles and debris in the water before they reach the pump, providing better overall filtration. Pre-filters help keep your pump cleaner and maintain your fountain's flow rate in between cleanings. Compatible with the Drinkwell 360 Plastic Fountain; not compatible with the Drinkwell 360 Stainless Steel Fountain. Trust PetSafe to help keep your pet healthy, safe and happy.