[Compatibility]: This replacement filter is only compatible with 230oz 1.8GAL 7L dog water fountain with 5-layer filter; [Four Layers of Filtration Ensure That Every Drop of Water Is Fresh]: Activated carbon eliminates bad odors; non-woven fabric captures pet hair and impurities; sponge filters debris to prevent clogging and damage to pump. Provides maximum protection for your pet's healthy drinking water; [6-Pack/12-Pack Water Fountain Filter Replacement]: Includes 6/12 replacement filters, 6/12 replacement pre-filter sponges, and 6/12 mesh filters. Multi-stage filtration helps ensure pets drink fresh, clean water; [Frequency of Replacement]: Soak the filter in water for 5 minutes before first use and rinse thoroughly under running water. Replace the water fountain filter every 1–2 weeks in summer and every 2–4 weeks in winter to maintain clean drinking water. Replace more frequently if multiple pets use the fountain.