Miller Center Guided Valves have only FOUR part: the body, the seat ring, the specially designed conical spring and the streamlined center guided disc. The valve has only ONE moving part, the integral guided disc.  The Miller Manufacturing Company, Inc., Center Guided Check Valve reflects the results of ong research, experience and study in the controls of fluids of all types.  Their use permanently corrects the disadvantages and inherent trouble found in other types of check valves - no internal screws or bolts to corrode in place, or work loose to cause costly damage.  Miller Center Guided Check Valves are designed to meet the requirements of the general rules and regulations as specified by the Board of Supervising Inspectors, Washington D.C., by the Fire Fire Underwriters, U.S. Coast Guard Marine Service and meet all code requirements.  They are used for all pressured up to 6000 pounds and at any temperature to handle all liquids and gases, hot or cold, oil, gasoline, acids, chemicals, gases of all types, air, salt water, brine, etc.  They are specified by leading Mechanical and Operating Engineers as standard equipment for Water Works, Industrials, Oil Refineries, Public Utilities (Power and Gas), Paper Mills, Hotels, Office and Public Buildings, Hospitals, Sugar Refineries, Breweries and Distilleries, Steamship Lines, Air Conditioning Systems and wherever permanent, low maintenance, shock-proof operation is essential.  All parts are removable and renewable.  All parts are precision machined and are interchangeable in the same size and pressure valve...a tremendous money saver.