Airbag for a vehicle occupant safety system

An airbag (10) for a vehicle occupant safety system comprising an inflatable cushion (11), a cinch tube (14) provided one in the pad (11) vent (15) surrounds, and a pulling element (18) in is coupled out to the peripheral channel (19) of the cinch tube (14) and to a surface of the pad (11) such that deployment of the cushion (11) the tension element causes (18), pull the cinch tube (14) , The airbag (10) comprises a kontraktionsbegrenzende assembly (21), which open for limiting the contraction of the cinch tube (14) through the pull member (18) to a predetermined minimum free diameter d of at least 20% relative to the free diameter D is cinch tube (14) is arranged.