Features: Made from premium cotton, active carbon, and resin, can effectively remove hair, debris, dirt, and other particles in water. The coconut shell activated carbon adopted has more pores and quicker absorbing speed, more durable than ordinary active carbon. The side length of the cat water fountain filter is 12.5cm/ 4.92inch, and the diameter of the center circle is 3.3cm/ 1.3inch. Broad compatibility, suitable for most square pet water fountains, always provide fresh and clean water for cats and dogs. Wash the filter before use, and change filters every 2-4 weeks, for the sake of pets' health. Specifications: Color: White Material: Cotton & active carbon & resin Product Size: 12.5 * 12.5 * 0.5cm/ 0.4 * 0.4 * 0.01inch (single one) Product Weight: 13g/ 0.45oz(single one) Note: The water fountains showed in the pictures are not included. Package List: 4 * Filter