This device supplies a controlled amount of air to the idle and main jets of each carburetor. The device has 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, causing the membrane to inflate, which opens the valve supplying additional air to the jets.
This not only makes the mixture leaner, but also improves the mixing of air and fuel. This air flow regulator is completely autonomous and is activated only by changes in ambient air pressure.
(You will find the original on the portal HondaBook.ru)