An impact absorbing device includes a plate and a panel having a panel thickness. An intermediate portion has a portion thickness and extends between the plate and the panel. The intermediate portion defines a chamber between the plate and the panel. A port is in communication with the chamber. The portion thickness is less than the panel thickness. The impact absorbing device is movable to a deployed position to contact an occupant during a collision. Since the portion thickness is less than the panel thickness, the intermediate portion expands more quickly, providing an impact surface for the occupant.