@Hackerman the original design, OG and Ti's 1 and 2, relied heavily on the airport.
The air flow under the cap was very restricted and the airport created the necessary pressure drop behind the screen which helped draw the vapor from the load.
The same principle is used in many places from grit blast and paint spray guns to carburettors and vacuum cleaners.
The evolution of the tips has meant more airflow and less need for the airport.
Personally I find the experience unsatisfying and ditched the 'carb'.
At the end of the day its each to their own.
The inclusion of the 2mm hole and the 'needle valve' design of the Omni condenser allows for the tailoring of the draw resistance/pressure drop ratio to individual needs.
This stem has no carb and the condenser is narrower than DV and my own regular stock size.