Hummer 2008 H2 Owner's Manual page 48

A booster seat (C-D) is a child restraint designed to
improve the fit of the vehicle's safety belt system.
A booster seat can also help a child to see out the
window.
1-44
Securing an Add-On Child Restraint in
the Vehicle
CAUTION:
{
A child can be seriously injured or killed in a
crash if the child restraint is not properly
secured in the vehicle. Make sure the child
restraint is properly installed in the vehicle
using the vehicle's safety belt or LATCH
system, following the instructions that came
with that restraint, and also the instructions in
this manual.