If the impact sensors, which are elements of the airbag system, detect a frontal or side impact that exceeds a predetermined level, they give an electrical signal to turn on the gas generators of the corresponding airbags and curtains. The gas generator provides opening and inflation of a cover of a pillow then the pillow is quickly blown off. Airbags are disposable devices and cannot be reused. Once deployed, the airbags become inoperative and must be replaced. To replace airbags, contact only an authorized Mazda dealer.