The cheap good variant
The rubber grommet is ideal if you have to use the air hose through the sheet metal,
But would like to save the slightly more expensive bulkhead penetrations or do not want to separate the tube
10mm tubing fits perfectly
No moisture penetration.
Tip: In a piece of 10mm PU hose you can ideally insert a 6mm hose, and so with these rubber also 6mm hoses at this point clean and tightly laying.