Keep your aquarium's water clean and healthy with Top Fin RF-L Large Retreat Filter Cartridges. These cartridges are easily replaceable, and feature coconut shell activated carbon, which serves to absorb undesirable odors, pigments and chlorine. Features: Coconut shell activated carbon to help absorb undesirable odors, pigments and chlorine 6 month supply Includes: 6 Count Intended For: Aquariums Color: White Product Dimensions: 7.9 in L x 2.7 in W (20 x 6.8 cm)