You piggy back off the regulator valve of the guy in front of you, It’s like a quick disconnect air valve.
On the submarine the have non skid on the decks, so when there is zero visibility in a fire, you put on the emergency breathing mask and you shuffle down the passageway piggybacked on the regulator of the guy in front of you, mind you there is no O2 till the front man hits the non skid on the deck, reaches for the panel above him that he cant see and plugs in...
Yall get a breath and move on.. Lather rinse repeat.. then you put out the damn fire!
Gotta be in the genes AND upbringing AND training. Glad you survived.