cushion 29 supported by the retainer 68 the ignition enhancer combustion chamber housing 54 and the housing 56 for containing a secondary supply of a gas generant material including both the sidewall member 58 and closure 60 referring again to fig4 there is shown is a view of the airbag inflator 10 with the upper housing pellet retainer and upper cushion removed looking in the direction of arrow b in fig3 the annular filter 66 is shown located inside the cup shaped lower housing 12 extending circumferentially around the ignition enhancer combustion chamber housing 54 and the housing 56 for containing a secondary supply of a gas generant material the ignition enhancer combustion chamber housing 54 is shown to have a substantially circular cross section however the housing 56 for containing a secondary supply of a gas generant material has a cross section that is not circular in this embodiment the housing 56 for containing a secondary supply of a gas generant material has a cross section that is substantially elliptical with the minor axis of the ellipse aligned with a radius of the ignition enhancer combustion chamber housing 54 to allow the diameter of the cup shaped lower housing to be reduced over what it would be if the housing 56 for containing a secondary supply of a gas generant material were circular in cross section and contained the same volume of gas generant material.