This is a BRAND NEW Honeywell Rheem/Ruud/Weather King/Corsaire furnace Gas Valve . The Honeywell Model # is VR8205T5801 and the Rheem/Ruud Part # is 60-100394-03. It has a 1/2" inlet and 1/2" outlet and is 4 1/8" Long. Valve is set up for NAT gas. Thanks for looking and good luck!
The gas valve is a low voltage control (usually 24 VAC) that allow gas into the combustion chamber. It is also an adjustable regulator that insures proper gas pressure for combustion. They have a manual shut off.