24 Packs premium charcoal water filter compatible with Drinkwell pet fountain Compatible models: Drinkwell Original, Platinum, Big Dog, Multi-Tier, Outdoor Dog, Mini, Everflow and Zen Pet Fountains Food grade activated carbon water filter removes bad tastes and odors from water, keeping it fresh; change every 2-4 weeks to maintain water freshness Nispira branded filters contain 50% more carbon than generic brands for better and longer-lasting filtration 100% customer satisfaction guaranteed. Quality meets or exceeds leading national brand 24 Packs premium charcoal water filter compatible with Drinkwell pet fountain. Compatible models: Drinkwell Original, Platinum, Big Dog, Multi-Tier, Outdoor Dog, Mini, Everflow and Zen Pet Fountains