Size: The size of the fountain filter is 12.7 x 12.7 x 1 cm, and the diameter of the center circle is 3.8 cm. Measure your fountain and check if the filter can be built into your fountain before ordering. (Attention: Does not fit “Catit” fountain.) High Quality: Replacement filter uses non- natural woven fabrics, coconut shell activated carbon and ion exchange resin. It can catch pet hair and dust, effectively filter dirt and remove bad odors in the water. Easy to use: Just put the raised side up and the side flat down, easy to install. Rinse the filter with water before use. Tips: We recommend changing the replacement filter every 2-4 weeks to keep the water clean. pet drinking water and help your pets love drinking water. -Cat Water Fountain Filter 12 Pieces.The internal material of the filter increased by 30%.The raised material can help improve the efficiency of filtered water. Extend life and provide pets with clean water. -Filters continuously clean and soften tap water to