Cat Water Fountain Filters for Veken 67oz, 95oz, 135oz Automatic Pet Fountains. 12 Replacement Charcoal and Resin Filters & 12 Pre-Filter Sponges (12 Sets). Includes 12 pack of replacement charcoal and resin filters + 12 packs of replacement pre-filter sponges. Thoroughly remove hair, dirt and other impurities, and keep water tasting fresh and clean all the time. Charcoal removes bad tastes and odors, and resin soften the water to deliver the highest quality water for your furry friend. Soak the filter for 5 minutes before use. To maintain the filtering effect, recommended to replace the filters every 2 weeks.