Bundle includes: 2 Bio-Foam, 2 Fine Foam, 2 Carbon Cartridges. The Fluval Nano Bio-Foam Filter Media Insert was specifically designed to fit inside the Fluval Nano Filter. It works to capture debris for effective mechanical filtration, plus it has large surface areas that encourage the proliferation of friendly nitrifying bacteria, which provide efficient biological filtration. The Fluval Nano Bio-Foam Filter Media Insert fits perfectly inside the filter chamber to prevent debris bypass. Bio-Foam allows efficient water flow, less clogging and long-lasting filtration. The Fluval Nano Fine Foam Filter Media Insert was specifically designed to fit inside the Fluval Nano Filter. It works to trap small sediments and debris for effective mechanical filtration, the crucial first stage in the filtration process. The Fluval Nano Fine Foam Filter Media Insert fits perfectly inside the filter chamber to prevent debris bypass. The foam pad has a pore size that allows efficient water flow, less clogging and long-lasting filtration. Specifically designed to fit inside the Fluval Nano Filter, the Fluval Nano Carbon Cartridge Filter Media Insert contains highly porous carbon that effectively adsorbs odors, discolorations and impurities. The Fluval Nano Carbon Cartridge Filter Media Insert's large surface area in the carbon effectively remove heavy metals, organic contaminants and pollutants, leaving aquarium water crystal clear and sparkling. The custom designed cartridges easily load into the Nano Filter's filtration chamber.