Premium Biological and Mechanical filtration media Designed specifically for the Fluval 406, 407 canister filters Convenient value pack format 6-month supply For use in freshwater and saltwater aquariums Bio-Foam Max: 2-in-1 Biological and Mechanical Filtration Media Rippled surface pattern offers 30% more area for increased debris and waste capture Bio-Foam: Mechanical Filtration Media Precision cut (no gaps) to prevent debris bypass Complex foam structure maintains consistent water flow Bio-Foam+: Mechanical and Biological Filtration Media Large porous surface supports expansive beneficial bacteria growth