GMC 2007 Yukon XL Owner's Manual page 95

If your vehicle has a roof-mounted rollover airbag
and a third row passenger seat, the airbag is
located in the ceiling above the rear windows for
the outside passenger positions in the third row.
CAUTION:
{
If something is between an occupant and
an airbag, the bag 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. And, if your vehicle
has roof-mounted rollover airbags, never
secure anything to the roof of your
vehicle by routing the rope or tiedown
through any door or window opening.
If you do, the path of an inflating side
impact airbag will be blocked. The path of
an inflating airbag must be kept clear.
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