Chevrolet 2007 Optra Owner's Manual page 24

3. Pick up the latch plate and pull the belt across
you. Do not let it get twisted.
The lap-shoulder belt may lock if you pull the
belt across you very quickly. If this happens,
let the belt go back slightly to unlock it.
Then pull the belt across you more slowly.
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4. Push the latch plate into the buckle until
it clicks.
Pull up on the latch plate to make sure it is
secure. If the belt is not long enough,
see Safety Belt Extender on page 37.
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.
5. Move the shoulder belt height adjuster to the
height that is right for you. Improper shoulder
belt height adjustment could reduce the
effectiveness of the safety belt in a crash.
See Shoulder Belt Height Adjustment
on page 31.