Extend the life of your filter and prevent premature clogging with the Fluval Pre-Filter. Designed specifically to capture solid waste and organic debris before they reach other media, these pre-filters will save you time and money since you won’t have to replace your filter quite as often. Not only will they help you save wear and tear on your filters, they also keep your water crystal clear so you can enjoy your aquarium and marine life the way they were meant to be seen. Ideal for medium and coarse filtration, these pre-filters will remove dangerous contaminants from the water, leaving a fresh and healthy environment. The Fluval Pre-Filter works with both freshwater and marine environments and is designed for the following filter models: 105, 205, 305, 405, FX5, 104, 204, 304, 404, 103, 203, 303, 403, 106, 206, 306, 406.