Airbag cushion for seat belt

An airbag cushion for a seat belt, comprising:

• a main bag including a center chamber at a central portion thereof, and side chambers provided on opposing sides of the center chamber, the side chambers being in communication with the center chamber in such a way that, in the event of a vehicle collision, the side chambers are first filled with a gas and, subsequently, the gas flows from the side chambers to the center chamber, thereby filling the center chamber with the gas;
• an upper tether extending to cover a first surface of the main bag;
• and
• a lower tether extending to cover a second surface of the main bag, the lower tether attached to the upper tether to define the main bag between the lower tether and the upper tether
• wherein each of first and second ends of the center chamber comprise a webbing hole into which a webbing is fitted.