GMC Hummer H3 2008 Owner's Handbook Manual page 153

Seats and Restraints
These are dual-stage frontal air
bags which adjust the amount of
restraint according to crash severi-
ty. For moderate frontal impacts,
the air bags inflate at a level less
than full deployment. For more
severe frontal impacts, full deploy-
ment occurs.
Vehicles fitted with dual-stage air
bags have a seat position sensor
for the driver's seat which aids in
determining whether the air bags
should inflate at reduced or full
deployment.
Vehicles fitted with dual-stage air
bags also have electronic frontal
sensors which help the system
distinguish between a moderate
and more severe frontal impact.
. . . 152
Your vehicle is also fitted with two
roof-mounted side impact air bags
that may inflate during a moderate
to severe side collision or a vehicle
roll-over to protect the driver, the
front passenger and the two
passengers directly behind them.
When an air bag inflates, the doors
may automatically unlock. The
interior lights and the hazard
warning flashers may also turn on.
You can lock the doors, turn the
interior lights off and turn the
hazard warning flashers off by
using the controls for those
features.