Penn Plax Cascade 400 Internal Filter Replacement Cartridges</br></br><div style="text-align:left"><b>[Product Information]</b><br><ul><li>Keep your water clean and clear with the replacement bio sponge for use in the Cascade 400 GPH Model CIF2 Internal Filter.</li><li>The bio sponge filter removes ammonia and nitrites from your aquarium tank keeping your aquarium clean; healthy; and odor free.</li><li>Filter sponge optimizes the colonization of beneficial aerobic bacteria which prevents the water from becoming cloudy and harming fish.</li><li>Perfectly cut to fit into the Cascade 400 Internal Filter tray without any gaps which could allow pollutants to re-enter the water.</li></ul></div></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br><img src='http://ecx.images-amazon.com/images/I/51uKMh18AtL.jpg' noproxy></br>