HC550 HydroClean Toilet Fill Valve saves water and detects leaks. It Installs quickly and easily without tools, eliminating guesswork. The easy calibration assures a full flush power. It is designed for areas of the country where the water supply is free of iron, bacteria, sediment and other particulate matter and does not need the Tank Cleaning Turbo Jet technology offered with the HydroClean HC660 model.