Gas generator for an air bag

A dual-type gas generator for inflating air bags is provided in which a first igniter structure (21) having a first combustion chamber (30) accommodating a first gas generating material (33) and a second igniter (41) structure having a second combustion chamber (40) accommodating a second gas generating material (43) both exhaust, when activated, to exhaust gas to a common filter chamber (50). The igniter structures (21,41) are intended to be activated separately and usually with a time lag such that gas generated in the first chamber (30) often flows into the second chamber (40) where it can cause ignition. This is a malfunction which is prevented by various flame-transferring preventing structures precluding direct flow of gas from the first chamber (30) into the second chamber (40) through the common filter chamber (50).