The Marineland Magnum 200 Rite-Size TC Replacement Sleeve fits the Marineland Magnum 200 Polishing Internal Canister Filter. This Rite-Size TC Floss Sleeve is specifically designed with fine mesh that traps and holds small dirt particles, while the sleeve’s open cell construction promotes water flow without impairing overall filter performance. This sleeve prolongs filter media life. For the best results, change the sleeve monthly.