An apparatus for helping to protect an occupant of a vehicle having a seat (16, 22) for receiving the vehicle occupant, the apparatus comprising: an inflatable vehicle occupant protection device inflatable from a stored condition to a deployed condition in which the protection device is inflated and positioned between a reaction surface of the vehicle and any occupant of the vehicle seat (16, 22), the protection device comprising: a rear portion positioned adjacent or near the reaction surface when the protection device is in the inflated and deployed condition; and a front portion positioned between the rear portion and any occupant of the vehicle seat (16, 22) when the protection device is in the inflated and deployed condition, the front and rear portions (62, 64) having a spaced configuration in which there is an open space outside the inflatable volume between the front and rear portion (62, 64) when in the inflated and deployed condition, wherein the front portion can move relative to the rear portion into the open space in response to occupant penetration and against pressurization forces within the protection device, wherein in the inflated state the front portion includes a front panel or surface presented towards the occupant, wherein the protection device further comprises a connecting portion positioned between the front and rear portions (62, 64), characterized in that the connecting portion interconnects the front portion and the rear portion at the upper extent of the front and rear portions, such that the protection device has a generally curved U-shaped or hook-shaped configuration when in the inflated and deployed condition, and such that the protection device has a generally inverted U-shaped configuration, wherein the lower extent of the front portion extends vertically below the lower extent of the rear portion. a rear portion positioned adjacent or near the reaction surface when the protection device is in the inflated and deployed condition; and a front portion positioned between the rear portion and any occupant of the vehicle seat (16, 22) when the protection device is in the inflated and deployed condition, the front and rear portions (62, 64) having a spaced configuration in which there is an open space outside the inflatable volume between the front and rear portion (62, 64) when in the inflated and deployed condition, wherein the front portion can move relative to the rear portion into the open space in response to occupant penetration and against pressurization forces within the protection device, wherein in the inflated state the front portion includes a front panel or surface presented towards the occupant, wherein the protection device further comprises a connecting portion positioned between the front and rear portions (62, 64), characterized in that the connecting portion interconnects the front portion and the rear portion at the upper extent of the front and rear portions, such that the protection device has a generally curved U-shaped or hook-shaped configuration when in the inflated and deployed condition, and such that the protection device has a generally inverted U-shaped configuration, wherein the lower extent of the front portion extends vertically below the lower extent of the rear portion.