Waste and dirt particles can build up over time, clogging your filter and requiring replacements more often than necessary. Prolong the life of your filter and protect the delicate balance of your marine ecosystem from the harmful effects of debris with Marineland's Bonded Foam Sleeves. The fine mesh foam traps debris before it gets to the filter, keeping it cleaner longer. The sleeve's open-cell construction encourages water flow, so it won't negatively impact your filter's performance. Keep your fish healthy and spend less time and money replacing your filters with these Bonded Foam Sleeves. Affordable and easy to use, this insert is designed to work with all H.O.T. Magnum Canister Filters. For best results, we recommend replacing the sleeve monthly. Marineland has been an innovator in the aquarium industry for more than 40 years.