Feature: Excellent water permeability, filter cotton can absorb impurities in water, alleviate water yellowing, and play the role of water purification. Stable water quality, removing chlorine, reducing the content of ammonia nitrogen and nitrite can balance the pH value of water. It has the best effect on decomposing the excrement and the forage leftover, remove the odor, bamboo charcoal can effectively absorb the odor, alleviate the odor of water, and use it well, so that your fishbowl is fresher. Scope of application: seawater tank, aquatic tank, freshwater fish tank. Can be cut any size as your needed. Guarantee: If you have any questions about this product, please feel free to contact us, we will try our best to help you solve your problem. Specification: Item name: Fish Tank Biochemical Filter Sponge Quantity: 2PCS Material: PolyurethaneBlack part is activated carbon coating) Size: 40*30*2cm/15.7*11.8*0.78in(1 pcs) Package information: Package size: 41*31*5cm(2pcs) Package weight: 195g Package Including: 2* Fish Tank Biochemical Filter Sponge