The Fluval C2 Poly Foam Pad Replacement Media, 3-pack, has two sides that combine to provide thorough and effective mechanical filtration. The Fluval C2 Poly Foam captures large particles of debris on it porous foam side, while the polyester side filters out finer debris and contaminants. The Poly Foam Pad Replacement Media helps bring your fish a healthy and clean environment. The Fluval C2 Poly Foam Pad was made specifically for the Fluval C2 Power Filter.