Fluval Pre-Filter is designed to capture solid waste before they reach other media. This prevents premature clogging of finer filters and extends their life, reducing media replacements frequency. Ideal for medium and coarse filtration. For freshwater and marine environments. For filter models: 106, 206, 306, 406, FX5, 105, 205, 305, 405, 104, 204, 304, 404.