sentences:  The bag is attached to a tube, connected to the oxygen source in the compartment, allowing for it to drop down and hang in front of the passengers.To operate on all aircraft except the L-1011 and B787, they must be pulled sharply toward the passenger who needs it to un-clip the flow pin and start the process of transporting the oxygen to the passenger.Passenger oxygen masks cannot deliver enough oxygen for sustained periods at high altitudes.