1. Perfectly designed and fit the corresponding Canister Filter;Compatible with AMOSIJOY Aquarium Canister Filter (172/225/265GPH); Compatible with Coospiderrepta Canister Filter(172/225/265GPH) 2. Fourlayer filtering 1. The White floss pads: trap most visible debris particles without restricting water flow and filter out fine particles providing crystalclear water. 2. Activated Carbon Sponge Bio Filter Pads: These filter pads contain doublelayer activated carbon, which can absorb impurities and odors in the water, reduce fishy odor and yellow water problems, and provide a and clean environment for fish. 3. The Removing Ammonia Pad absorbs the harmful ammonia. 4. Reducing Phosphate Pad absorbs excess Phosphate. 3. The refill kit contains 2 pieces of activated carbon bio pads, 4 pieces of white floss pads, 1 Removing Ammonia Pad, and 1 Reducing Phosphate Pad.