An airbag 10 includes at least one panel 12 defining an interior 104/102 of the airbag, and a divider 100 positioned in the interior so as to divide the interior into an upper chamber 102 and a lower chamber 104. A valve mechanism 200 is operatively coupled to the divider 100 for restricting a flow of gases from the lower chamber 104 into the upper chamber 102. The valve mechanism 200 includes one or more valves 200 with a desired aggregate opening(s) and located in predetermined location(s) thereby affecting a designed inflation profile. The divider 100 has an arcuate length Ld, measured between two divider airbag attachment points 100d and 100a, greater than a corresponding linear horizontal airbag length La, measured between the same two attachment points. The passenger side airbag 10 for each unique vehicle is designed by iteratively reconciling the requirements of FMVSS208 with the present airbag design.