The Fluval AquaClear Freshwater and Saltwater Active Carbon for AC50 Aquarium Power Filter replacement carbon media is for AquaClear 50 filters. These high-quality activated carbon inserts improve water clarity by removing discoloration, odors, and toxic impurities from aquarium water. They are custom-fit for AquaClear filters to ensure maximum contact time and efficient adsorption of dissolved contaminants, leaving the water clean and crystal clear. Available in Singular and 3-Pack Option