The PetSafe Drinkwell Replacement Foam Filters trap any large debris and hair in the water, before they reach the pump, providing cleaner water to your pet. These foam filters help keep the pump cleaner in between cleanings and maintain the fountain's flow rate. They are sold in a 2-Pack and are compatible with the PetSafe Drinkwell Avalon, Pagoda, Sedona, Seascape and Stainless Multi-Pet Fountains.