GMC Hummer H3 2008 Owner's Handbook Manual page 146

The lap/shoulder belt should be
worn as shown above.
CAUTION
Belts should not be worn with
straps twisted.
Wear your belt fitted closely
against the body. Do not wear
your shoulder belt under your
arm. Make sure the belt is not
twisted across your body.
The shoulder belt should go over
the shoulder and across the chest.
These parts of the body are best
able to take belt restraining forces.
The shoulder belt should not cross
the face or neck.
CAUTION
The lap part of the belt should
be worn low and snug on the
hips, just touching the thighs.
In a crash, this applies force to
the strong pelvic bones, and
you would be less likely to slide
under the lap belt. If you slid
under it, the belt would apply
force to your abdomen. This
could cause serious or even fatal
injuries.
Section 2
A
Shoulder Belt Height Adjuster
Your vehicle may be fitted with
shoulder belt height adjusters.
This adjusts the height of the front
shoulder belt. You should adjust it
so the belt is centred on your
shoulder and away from your face
and neck.
To move the height adjuster
down, press the release button
and slide it down to the proper
height.
145 . . .