Package Contents: Set of 6 cat fountain filters, divided into independent packages, hygienic and clean, providing more protection for your pets. PERFECT ASSORTMENT: There are 6 of our filters compatible with the 43717 fountain filter. Please check the model of your fountain before purchasing. Triple-Effect Filter: filter products Triple-effect filters use non-woven fabrics, activated carbon and natural resins to effectively purify water, while the cotton fabric on the outer layer of each filter can capture debris. Make sure the cat's water is pure. Instructions for use: Thoroughly immerse the fountain filter in the cat's water before use, then carefully connect it to the fountain. To ensure clean water, the filter should be replaced regularly. 1 to 2 weeks in summer and 2 to 4 weeks in winter.