Dimensions: The fountain filter measures 4" x 4" x 0.75" and the diameter of the center circle is 0.75". Measure your fountain and check if the filter can be built into your fountain before ordering. Compatibility: Compatible with 2.5L Round Stainless Steel Cat Fountain and Plastic 2.5L Cat Fountain 2L square flowers. Not suitable for 1.6L flower fountain and 2L 0.4L flower fountain. High quality: The replacement filter uses a natural non-woven fabric, coconut shell activated carbon and ion exchange resin. It captures pet hair and dust, effectively filters dirt and eliminates odors in the water. Easy to use: just place the raised side up and the flat side down for easy installation. Rinse the filter with water before use. TIP: We recommend changing the filter every 2-4 weeks to keep the water clean. Han Tuo always pays attention to the health of pet drinking water and makes your pet fall in love with drinking water. Scope of delivery: 8 filter sponge cores, white