SIZE: 13*13*8.5 cm / 5.1*5.1*3.4 in. KEEP YOUR PET HEALTHY: Each filter is composed of a cotton layer, activated carbon, and an ion exchange resin. They can filter hair, heavy metals, and improve the taste of the water so that pets can drink clean and fresh water all day, which helps to increase water consumption and reduce the risk of urinary tract infections. RECOMMENDATIONS: To prevent the activated carbon dust (which will not harm your pets) from shedding into water, please soak the filter in water for 2 minutes and rinse it thoroughly under running water before use. According to your pet's drinking frequency and number of pets using the fountain, change the filter every 2-4 weeks Compatibility: Compatible with most square pet fountains.