[Compatibility] These pet water fountain filters are compatible with 135 fl oz/4L cat water fountain.Size:3.8x3.4Inch. Please make sure the size and model are appropriate before purchasing. [Multiple Filtration Systems] Non-woven fabric can filter pet hair and fine debris, activated carbon can get rid of the odor of the water, the role of pure water, ion exchange resin can filter heavy metals, improve the quality of water, keep the water clean and fresh. [Further Water Purification Function] Pre-filter sponge can further filter out impurities to avoid impurities entering the pump, thus extending the life of the pump. [Replace Regularly] Please soak in water for 5 minutes and rinse well before use. For your pet's health, we recommend changing the filter every 2-4 weeks. If there are multiple pets, they will need to be replaced more frequently.<br><br>Colour:White Material:Plastic<br><br>Package Contents: 12 * filter elements 12 * sponge pads 12 * sponges<br><br>Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.