Thermostatic radiator valves are used for use on hot water one-pipe & two-pipe low pressure steam systems. Helps regulate flow of hot water or steam through free-standing radiators, baseboards or convectors in hot water and two-pipe low pressure steam systems. Valves are fitted with packing gland assembly that allows replacement while system is in operation. Packing gland is fitted with a grease cup to ensure the o-ring packing is lubricated for life. Sturdy EPDM rubber valve disc provides a positive seal against the valve seat at differential pressures of up to 20 PSI in Hydronic hot water heating systems. Includes plastic cap to protect valve pushpin and to provide manual control of valve during installation. Conforms to ASHRAE/ANSI standard 102-1983.