Hummer H2 2009 Owner's Manual page 52

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.
1-48
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. Secure the child restraint properly in the
vehicle using the vehicle's safety belt or LATCH
system, following the instructions that came with
that child restraint and the instructions in this
manual.