Want aquarium water so crystal clear that it looks like your fish are swimming in a tank of air? The ABN Sock Filter – 200 Micron PP with Plastic Ring 4” x 13” Inch – For Fish Tank, Aquarium, Refugium, Sump Pump does the hard work for you so your fish stay happy and healthy. This 4" x 14" felt sock filter with a 4" diameter plastic ring fits most sump and refugium holders for easy suspension and all filtration needs. The interlocking felt fibers reduce micro bubbles and trap uneaten food, waste, decay, dust, and other particulates but allows water to flow through. This polypropylene (PP) 200-micron non-woven synthetic felt fiber filter does not clog as quickly as smaller micron filters and lasts longer than polyester filters. Wash with hot water and no detergent soap.