GMC 2010 Sierra Owner's Manual page 119

Driver Side shown, Passenger Side similar
If the vehicle has roof-rail airbags for the driver, right
front passenger, and second row outboard passengers,
they are in the ceiling above the side windows.
WARNING:
If something is between an occupant and an
airbag, the airbag might not inflate properly or it
might force the object into that person causing
severe injury or even death. The path of an
inflating airbag must be kept clear. Do not put
anything between an occupant and an airbag, and
do not attach or put anything on the steering
wheel hub or on or near any other airbag
covering.
Do not use seat accessories that block the
inflation path of a seat-mounted side impact
airbag.
Never secure anything to the roof of a vehicle with
roof-rail airbags by routing a rope or tie down
through any door or window opening. If you do,
the path of an inflating roof-rail airbag will be
blocked.
2-77