GM Chevrolet Avalanche - Manual (Page 29)

To make the belt shorter, pull its free end as shown
until the belt is snug.
Buckle, position and release it the same way as the lap
part of a lap-shoulder belt. If the belt is not long
enough, see Safety Belt Extender on page 1-28.
Make sure the release button on the buckle is positioned
so you would be able to unbuckle the safety belt
quickly if you ever had to.
Rear Seat Passengers
It is very important for rear seat passengers to buckle
up! Accident statistics show that unbelted people in
the rear seat are hurt more often in crashes than those
who are wearing safety belts.
Rear passengers who are not safety belted can be
thrown out of the vehicle in a crash. And they can strike
others in the vehicle who are wearing safety belts.
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