Compatible Only with Smartoo 152oz/4.5L Cat Fountain PTM-643 – Specifically designed for this model to ensure a perfect fit and optimal performance. Please check dimensions before purchasing. Length is about 4.20 inch. Width is about 4.00 inch. Thickness is about 0.25 inch. Advanced 5-Layer Filtration System – Includes a pre-filter sponge, cotton layer, activated carbon, medical stone, and ion exchange resin to effectively remove hair, heavy metals, and impurities while improving water taste. Helps Maintain Fresh and Clean Water – Filters out dirt and debris to keep your pet’s drinking water pure and healthy, encouraging proper hydration. Regular Replacement for Best Results – Soak the filter in water for five minutes before use and replace every 1-2 weeks in summer or 2-4 weeks in winter. More frequent changes may be needed for multi-pet households. Ensure your feline friend enjoys fresh, clean, and great-tasting water with the PET STANDARD Replacement Water Filter & Pre-Filter Sponges. Designed exclusively to be compatible with the Smartoo 152oz/4.5L Automatic Cat Fountain PTM-643, this high-quality filter system keeps your pet’s drinking water pure by effectively removing impurities, hair, and heavy metals. The advanced five-layer filtration system, including a pre-filter sponge, cotton layer, activated carbon, medical stone, and ion exchange resin, enhances water quality while improving taste. Regular filter replacement is essential to maintain optimal water freshness. Soak the filter for five minutes and rinse thoroughly before use to prevent activated carbon dust from shedding into the fountain. Replace the filter every one to two weeks in warmer months and every two to four weeks in colder months. If multiple cats share the fountain, more frequent changes may be needed. This premium 12-pack of pet fountain filters and 12-pack of pre-filter sponges come individually sealed to ensure long-lasting quality. With a supply lasting up to 12 months, you can provide your pet with clean, healthy water all year round. Keep your cat hydrated and happy with a reliable filtration system designed for superior performance and compatibility.