In addition to seatbelts, most vehicles today are fitted with airbags in the front seats as restraint devices for protecting occupants in frontal collisions. However, various constraints in the rear seats have prevented progress in adopting the same type of airbag system as that used in the front seats. Therefore, a new airbag system has been developed as a crash energy absorbing device to improve protection of the head and neck of rear-seat occupants. This new airbag system can be installed under the traditional constraints present in the rear seats.