ENHANCED COMPATIBILITY: Our cat water fountain filter replacement is compatible with pet water fountain 3L, featuring precise dimensions of 3.3" x 3.3" (L x W) for an accurate installation. Please note, there is no central hole design in this filter. MULTI-STAGE FILTRATION: Our cat fountain filters replacement are made of high-density activated carbon and ion exchange resin, wrapped in non-woven fabric, effectively isolating cat hair, food residue, and particles. They remove impurities, filter out heavy metals and odors, and soften tap water, ensuring your pet enjoys the more fresher, cleaner water. FOR PET'S OPTIMAL HEALTH: Crafted from high-quality, safe, and odorless materials, this pet water fountain filter is essential for maintaining water quality and safeguarding your pet's urinary system health. Keep your pets healthy with every sip. REPLACEMENT RECOMMENDED: To ensure a constant supply of clean water and maintain your pet's health, we recommend replacing the filters for cat water fountain every half to 1 month. More pets mean more frequent replacements. This ensures optimal performance of filters and prolongs the lifespan of your cat fountains for drinking. CUSTOMER SUPPORT: If you experience any issues with TOGGATH pet fountain filter replacement, our team is here to help. We offer exceptional after-sales service and are committed to ensuring your satisfaction. Please measure the size referring to the picture before buying.