It’s the VENTILATION nozzle.
Money Heist Season 1, Episode 5
even in the underground VENTILATION ducts.
Money Heist Season 1, Episode 11
They're putting tubes through
the VENTILATION pipes.
Money Heist Season 3, Episode 6
Pressure. I've turned the VENTILATION up
to keep the outside out.
Breaking Bad Season 3, Episode 10
or, if it went wrong, two dead bodies
inside the VENTILATION ducts."
Money Heist Season 1, Episode 6