Marineland Rite-Size U Foam Sleeves are designed to fit all H.O.T. Magnum Canister Filters. Each Rite-Size Foam Sleeve is specially designed to prolong the life of filter media by reducing the accumulation of waste and dirt particles which can prematurely clog a filter. Note: Magnum 350 uses Rite-Size V Bonded Filter Sleeve. Shipping weight: 1/5 lb.