Fluval 306/406 & 307/407 Bio-Foam+. Designed specifically for Fluval 306/406, 406/407 canister filters, Bio-Foam+ performs double duty as both an effective mechanical and biological media. Key Features : Mechanical/Biological filter media Dense structure ideal for trapping small particles Intricate, porous network provides vast surface area to facilitate growth of beneficial bacteria Helps create clean and healthy water conditions for fish and plants Convenient 2-pack format.