Abstract: An apparatus (20) for inflating an air bag comprises a housing (22) which includes a wall (84) having an inner surface defining a chamber (108). Ignitable gas generating material (122) is located in the chamber (108) and, upon ignition, provides combustion products including gas which flows from the housing to inflate the air bag and hot particles. A tubular filter (140) removes hot particles from the gas flow. The tubular filter (140) comprises a strip of material having a plurality of spaced openings (146) through which the gas can flow and two end portions (160, 162) which overlap. The strip of material also has a plurality of projections (142, 144) engaging the inner surface of the housing (22). The projections (142, 144) are located on the strip of material at spaced locations around the tubular filter (140). The projections (142, 144) space at least a portion (148, 150 or 152) of the tubular filter (140) away from the inner surface of the housing (22).