Compatible with Veken, automatic flower fountain and others of the same size. Size: 4.9 inches (length), 1.38 inches (inner diameter). Dual action filters: resin and activated carbon. The resin can soften the water and reduce the risk of stones. Activated carbon can absorb impurities and odors, keep water soft and clean. Water quality can be removed by the three 3 types of filtration. The outer cotton layer on each filter captures hair and debris. Three stages of filtration can ensure water quality and improve the taste of fresh water for your cats. Rinse the filter thoroughly with water before using, easy to assemble on a pet fountain. In order to ensure clean water, the filter should be replaced in time, please replace it within 2-4 weeks. < p>Specification: Name: Cat Water Fountain Filter Material: Activated Carbon, Resin Size: Length: 12.5cm, inner diameter : 3.5cm / 1.38in, thickness: 1cm / 0.31in