[COMPOSITION MATERIAL]:Each Pet Cat Fountain Filter And Dog Fountain Filter Is Composed Of A Cotton Layer, Activated Carbon, And An Ion Exchange Resin [PURIFYING PERFORMANCE]:Pet Cat Fountain Filter And Dog Fountain Filter Can Filter Hair,Residue,Removes Bad Tastes And Odors From Water, Keeping Water Fresh,So That Pets Can Drink Clean And Fresh Water [VALUE COMBINATION]:Our Pet Cat Fountain Filter And Dog Fountain Filter Are Packed In A Set Of 6/8/12 Pcs ,each Piece In Each Group Has Its Own Packaging,individually Packaged And Sealed To Maintain High Quality size: 4 9*1 3inch [REPLACEMENT FREQUENCY]:We Suggest Change Pet Cat Fountain Filter And Dog Fountain Filter 1 To 2 Weeks In Summer And 2 To 4 Weeks In Winter To Maintain Water Freshness [NOTE]:To Prevent The Activated Carbon Dust (which Will Not Harm Your Pets) From Shedding Into Water, Please Soak The Cat Fountain Filter In Water For 2 Minutes And Rinse It Thoroughly Under Running Water Before Use