The output valve is a valve usually found on the gas reservoir that is kept close by spring tension and the presence of high pressure gas. It acts as the gate that seals gas in or lets gas out. A spring loaded piston that seals the valve is struck by the replica’s hammer causing it to open for a brief amount of time.
Output valves come in different shapes and size depending on the replica or gas system they are used in. The ports can have different shapes and profiles that dictates the flow rate of the gas propellant.