This is a new White Rodgers Universal Furnace Gas Valve. The White Rodgers part # is 36C03300 and it is a direct replacement for the part #s below.
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.
V800A1021 V800A 1021