Package Content: You will receive 12 pieces of cat fountain filters with a triple filtration system. This quantity is sufficient to meet your usage and replacement needs, providing clean drinking water for your pets. Product Size: The cat water filter sponge measures 11.4 x 5.7 x 1.9 cm / 4.5 x 2.24 x 0.75 inch, compatible with 50 oz / 1.5 L WF-050 and WF-100 clear pet fountains. Please confirm the size before purchasing. Premium Material: The pet fountain sponge filters are made of high-density sponge, activated carbon, and ion exchange resin. These soft and reliable materials offer improved water purification for your pet. Filtration Function: Featuring high-density and high-content activated carbon, these pet fountain filters effectively remove hair, dust, heavy metals, and other impurities. Help keep your pet's water clean and fresh. Warm Tips: Please rinse the cat fountain filter sponge under water before use. Soak the foam filter for 5 minutes. It is recommended to replace the sponge filter every two weeks in summer and every three weeks in winter.