[Perfect Compatibility] Compatible with the HAPUP water fountain for cats and dogs. Encourages pets to drink more water and supports overall health. [Triple Filtration System] Each cat water fountain filter features a porous filter cotton layer, high-density cotton, high-quality activated carbon, and ion exchange resin. The cotton layer traps hair, sediment, and debris. Activated carbon reduces bacteria and removes chlorine odors. Ion exchange resin helps soften tap water and may contribute to reducing the risk of urinary tract issues. This system keeps your pet's drinking water clean and fresh. [Safe Premium Quality] Replacement cat water fountain filters are made from high-quality, non-toxic materials. Designed for easy visibility and simple cleaning. The black and white design helps indicate when cleaning or replacement is needed. Helps provide cleaner water and supports your pet's well-being. [Replacement Cycle] To minimize carbon dust, rinse the filter thoroughly under running water before use and soak for ten minutes (minor activated carbon residue is normal). Clean the HAPUP cat fountain weekly. Replace the filter every four weeks for optimal performance. [Bargain and Friendly Service] Pack of 6 pet fountain filters for long-term use.