DESC: The world's best selling power filter is the only one that offers the "one-two punch" of the CycleGuard Insert System - a combination of highly efficient filtration media, in conjunction with powerful water flows from the "Free Floating" impeller. A great system for removing organic toxins. Additional features make it easy to use: flow-control adjustment, a basket to hold all filter media in one accessible place, and a clear filter case to allow quick visual check of conditions. Depend on it for your salt or fresh water tank.