About this item Compatibility: Replacement filters are designed for 0.5/1/2.5/4 GAL gravity waterer, to keep water clean, fresh and tasty for your cats and dogs Triple Filtration System: Two high density cotton layer can filter particles and debris, keep water clean; Internal charcoal element controls chlorine and absorb odors, purify and freshen water for pets Warm Tips: Before replacing filter, please soak filter into clean water for two minutes, then rinse filter thoroughly, which will prevent carbon dust from shedding into water, keep water clean Replace Regularly: To maintain filtering effect, you need to replace filter every two weeks; If you have multiple pets, please change the filter and clean fountain more often Easy to Replace: It is easy to replace the filter, just take out the old filter, and put in the new soaking filter, and fix it with plastic strip.