GMC 2005 Canyon Owner's Manual page 45

A booster seat (F-G) is a child restraint designed to
improve the fit of the vehicle's safety belt system.
Some booster seats have a shoulder belt positioner,
and some high-back booster seats have a five-point
harness. A booster seat can also help a child to see
out the window.
Q:
How do child restraints work?
A:
A child restraint system is any device designed for
use in a motor vehicle to restrain, seat, or position
children. A built-in child restraint system is a
permanent part of the motor vehicle. An add-on
child restraint system is a portable one, which
is purchased by the vehicle's owner.
For many years, add-on child restraints have used
the adult belt system in the vehicle. To help
reduce the chance of injury, the child also has to be
secured within the restraint. The vehicle's belt
system secures the add-on child restraint in the
vehicle, and the add-on child restraint's harness
system holds the child in place within the restraint.
One system, the three-point harness, has straps that
come down over each of the infant's shoulders and
buckle together at the crotch. The five-point harness
system has two shoulder straps, two hip straps and a
crotch strap. A shield may take the place of hip
straps. A T-shaped shield has shoulder straps that
are attached to a flat pad which rests low against the
child's body. A shelf- or armrest-type shield has
straps that are attached to a wide, shelf-like shield
that swings up or to the side.
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