The Hydra Pools H03116N is an Aquagenie Winter Cover. Because of its revolutionary design, the Aqua Genie removes surface debris up to ten times faster than conventional skimmers. At the same time, it continuously feeds a precise amount of chlorine into the pool, assuring clean, healthy water without over-chlorinating. In short, the Aqua Genie is an entire pool-maintenance system, dramatically reducing the time you'd normally spend chlorinating and vacuuming your pool.