Hummer 2005 H2 Owner's Manual page 43

CAUTION:
{
Never do this.
Here two children are wearing the same belt.
The belt can not properly spread the impact
forces. In a crash, the two children can be
crushed together and seriously injured. A belt
must be used by only one person at a time.
Q:
What if a child is wearing a lap-shoulder belt,
but the child is so small that the shoulder belt
is very close to the child's face or neck?
A:
If the child is sitting in a rear seat outside position,
move the child toward the center of the vehicle.
Also, see Rear Safety Belt Comfort Guides
for Children and Small Adults on page 1-33. If the
child is sitting in the center position, move the
child toward the safety belt buckle. In either case,
be sure that the shoulder belt still is on the
child's shoulder, so that in a crash the child's upper
body would have the restraint that belts provide.
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