Abstract: A self-contained inflatable air bag apparatus that can be effectively used in virtually any vehicle having seat belts. The apparatus includes a base connected to the restraining belt; an inflatable air bag carried by the base; a source of pressurized gas; and a trigger responsive to a predetermined tensile loading of the belt for connecting the source of gas to the air bag, the air bag being expansively deployed for crash-protection of the occupant upon occurrence of the predetermined tensioning of the belt.