Key Features Compatible Pet Mate Filter Cartridge Pack of 2 Fits Cat Mate and Dog Mate Drinking Fountains Activated carbon for purification Essential for keeping your Pet Mate Fountains clean and operational KCT Compatible Replacement Filter Cartridges for Cat Mate Fountain - Part 335 .These compatible Cat Mate replacement filters are designed to work with your Cat Mate fountain. The active carbon works to remove chlorine, sediment and volatile organic compounds. If you have a Cat Mate Pet Fountain it is important to regularly replace the Carbon Filter Cartridges to keep the water clean and healthy for your pets. It is recommended to replace these every month, for two or more cats you may need to replace the filter more regularly. This prevents any build up of dirt and will prevent premature pump failure. Specifications Pack of 2 compatible replacement filters Compatible with the larger Dog Mate Fountains (Part Number 385) and the smaller Cat Mate Fountains (Part Number 335)