The safety belt pretensioners are actuated by a gas generator triggered by the
airbag control unit. The pretensioners have a lower deployment threshold than the front
airbags so that they may deploy in a collision that is not enough to deploy the front
airbags. When activated, the pretensioner tightens the webbing. Because the webbing is now tighter across the body, occupants participate earlier in the vehicle ride down and loadings on the body are distributed more uniformly over the entire restraint sequence, the risk of injury declines.