Reducing valves fill the system to a preset pressure for optimum performance. Combination Dual Unit Valves include pressure reducing valve and relief valve. B and G reducing valves protect heating and plumbing systems against excessive line pressures. They are factory set at specified limits although adjustment is easily made. Equipped with built-in-strainer and low inlet pressure check valve. Tail piece for union models is combination - 1/2 in cooper sweat and 1/2 in male NPT.