This device supplies a controlled amount of air to the idle and main jets of each of the carburetors. The device contains membranes that are sensitive to changes in air pressure associated with changes in altitude above sea level. As the altitude increases, the air pressure drops, which causes the membrane to inflate, from which the valve for supplying additional air to the jets opens.
This not only leans the mixture, but also improves air-fuel mixing. This air jet regulator is completely self-contained and is only actuated by pressure differences in the ambient air.