12 pack of foam pre-filters made for the Drinkwell Stainless Steel 360, Lotus, Avalon, and Pagoda pet water fountains. These pre-filters trap hair and other debris in the water, providing your pet with cleaner, healthier water, while also prolonging the life and flow rate of the filter pump. It is recommended to replace these every 2-4 weeks, depending on usage. This product is BPA-Free.