Worried about freshness of DODOINGing water in fountain? Worried about your pet getting sick? No worries our DODOING cat fountain filter will solve your problem. Designed with upgraded Triple Filtration System that included activated carbon ion exchange resin and cotton mesh. Material: Activated Carbon+Cotton Square shape: Package size: 13 * 8 * 13cm/ 5.12 * 3.15 * 5.12in Package weight: 85g Round shape: Package size: 13 *13*4cm/ 5.2 * 5.1*1.5in Package weight: 80g Package list: 4* Cat water fountain filter (Optional) TIP: Carbon dust or ion exchange resin may be released for the life of filter which is not harmful to your pet. Suggest: 1.Replacing Charcoal filters every 2 to 4 weeks to keep the water clean. 2.Replace more frequently if multiple pets using the fountain rinse filter with water thoroughly before use. 3.A small amount of carbon dust may be released for the life of filter which is not harmful to your pet.