An airbag assembly may include an airbag and an inflator that provides inflation gas to inflate the airbag. A filter module may be positioned such that inflation gas exiting the inflator must first pass through the filter module. The filter module may be formed of a sheet of metal that is wrapped into a generally tubular shape. The filter module may have a first layer and a second layer that generally encircles the first layer. The first layer may have a pattern of holes and dimples that are separate from and/or displaced from each other. The dimples may protrude toward the second layer to maintain spacing to enable relatively unrestricted gas flow from the holes of the first layer through unaligned holes of the second layer. The resulting tortuous gas flow path may help to slow, cool, and/or purify the gas before it exits the inflator.