The Fluval C4 Poly Foam Pad Replacement Media has two sides that combine to provide thorough and effective mechanical filtration, The Fluval C4 Poly / foam captures large particles of debris on it porous foam, while the polyester side filters out finer debris and contaminants, The Poly Foam Pad helps bring your fish a healthy and clean environment, The Fluval C4 Poly Foam Pad Replacement Media Features and Benefits:, - Provides thorough mechanical filtration, - Filters out debris, - Creates a healthy and clean environment for your fish, SKU: RCHG0216