The Gas Cylinder Adapter consists of a female 7/16 NS thread with a pin that depresses through the gas cylinder when the knob on the fitting is rotated in a counter clockwise direction, thus allowing inert gas to flow to a metering valve. There are 2 1/8” NPT female threads on the aluminum fitting. Typically one is for a pressure gauge and the other threads on to the metering valve. The aluminum gas cylinder cannot be used alone to meter gas into the tube. An additional valve that can handle a pressure of greater than 300psi must be used.