Keep your kitty's water fresh and pure in the Trouble & Trix Cat Water Fountain with the Trouble & Trix Cat Water Fountain Filter Pad. Coming in a pack of 3 replacement filters, it is recommneded to change the filter monthly to get optimum results. The Trouble & Trix Cat Water Fountain Filter Pad works to remove debris and impurities by filtering any particles out and it also absorbs bad odours and removes chemical impurities from tap water. Easy to change, the Trouble & Trix Cat Water Fountain Filter Pad will ensure your kitty has the freshest and tastiest flowing water possible.