Multi-layer Filtration for Tasty Water: The multi-layer filtration system can effectively remove impurities, odors, and heavy metals, ensuring your cats always drink fresh and healthy water and protecting them from urinary tract diseases. Replacement Reminder via App: Please rinse the filter with clean water before use. For the health of your cat, it is recommended to replace the filter every 2-4 weeks. The app will remind you to replace the filter on time.