Airbag with adjustable vent cross section

"IMPACT PROTECTION DEVICE FOR VEHICLE OCCUPANTS". A gas bag for a containment device for the occupants of a vehicle has a ventilation opening. An inelastic line is arranged on the outer surface of the gas bag (1) forming a loop (4) around the ventilation opening (2). Each end of the line is affixed to a part of the stretchable surface of the gas bag. The ventilation opening has a flow cross section that is likely to be reduced in proportion to an elastic expansion of the gas bag (1) as a result of internal pressure that is generated when a vehicle occupant dives or sinks into the gas bag inflated.