Buick 2003 Regal Owner's Manual page 29

When you sit in the center seating position, you have a
lap safety belt, which has no retractor. To make the
belt longer, tilt the latch plate and pull it along the belt.
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 isn't long
enough, see Safety Belt Extender on page 1-29.
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.
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