Package includes 30 packs of replacement cat fountain filters and 30 sponges. Depending on how often your pet drinks and how many pets you have, we recommend that you clean your pet fountain filters once a week and change them 1 to 2 times a month to keep the water fresh and clean. : The cat fountain filter measures 2.99 x 1.69 inches and the sponge measures 3.1 x 1.1 inches, compatible with most 67 oz/2 liter, 101 oz/3 liter, 108 oz/3.2 liter and 135 oz/4.0 liter stainless steel pet fountains on the market. Please check if it is compatible with your cat fountain before purchasing! EASY TO USE:This pet fountain filter replacement is very easy to install and remove, saving time and effort! Please soak the pet fountain filter and sponge in water for at least 3 minutes to promote optimal filtration, then rinse thoroughly under running water. This help keep your cat's drinking water fresh for longer. Triple Filtration System:The cat drinking fountain filter consists of a triple filtration system of activated carbon, sponge and non-woven fabric. They can help filter out impurities such as hair and food residue, absorb odors, and soften the water while improving the taste and quality of the water, helping to keep your pet healthy. Colour:Photo Color Material:Non-woven fabric + activated carbon + sponge Package Contents: 30 x runway Filter Elements 30 x circular Filter Elements Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.