A lightweight and inexpensive inflator for a vehicle passenger side restraint bag. The inflator includes a thin igniter housing member and also includes a thin arcuate barrier member which defines a combustion chamber for holding gas generant material for combustion thereof. The inflator housing has generated gas outlet apertures only on one side and the barrier member faces that side so that generated gas is directed toward the other side of the housing and is then redirected through a filter pack to the apertures. The filter pack includes a plenum providing screen which is blocked to the entrance of redirected gas by the pressing of other layers of the filter pack against the housing wall whereby the redirected gas is directed through a fibrous filter member before being directed into the plenum and out through the housing apertures. After leaving the housing apertures, the generated and filtered gas is directed through another filter pack which is disposed along the wall of the bag retainer prior to the gas flowing into the airbag.