Side airbags are installed in the seat outside in order to slow the side-impact damage. Many manufacturers models will come standard with front two seat side airbags, while assembling models of rear side airbags are rare.
Most models are equipped with only the main, passenger airbag, side airbags, vehicle frontal crash occurred in real time, here are more protected, following knee and the shortest distance of the center console, is the most easy to cause fracture site.
Knee airbag is used to reduce passenger car interior in the second impact on occupant injuries of the knee. Knees within the air bag is located in the front seat, if opened can effectively protect body parts under the rear passenger's waist, which can alleviate the positive momentum before the collision.