Abstract: A partitioned air bag (55) comprising an upper (54) and a lower (52) inflatable chamber, the lower chamber upon inflation is positioned to provide a cushioned boundary generally against the lower chest and abdomen of an occupant to be protected, the lower chamber first receiving inflation gas from a source of inflation wherein the inflation gas is sequentially transferred to the upper chamber through one or more ports (162) formed by a separator panel that separates the air bag into the upper and lower chambers. The air bag is inflated by a single stage air bag inflator (26) characterized as having a relatively low fill rate.