Side air bag with internal tether

A side air bag 1 has an internal tether 6 serving to interconnect two spaced-apart regions of the air bag, the distance around the periphery of the air bag, in horizontal section, between the ends of the tether being greater in one direction (anti-clockwise from point 7) than in the other direction (clockwise from point 7), the length of the tether being less than the shorter distance. The air bag may be located within the backrest 10 of a vehicle seat, and the tether serves to assist in guiding the air bag, on inflation, so that it extends forwardly from the seat to lie adjacent an occupant of the seat. The air bag may comprise two superimposed identical layers of fabric connected by a seam (figure 2), two layers of fabric connected by a third or gusset layer (figure 6), or two adjacent layers of fabric of different sizes (figure 8).