Mercury 1997 Cougar Manual page 118

While you are fastened in the seat belt, the
combination lap/shoulder belt with a cinch
tongue adjusts to your movement. However, if
you brake hard, turn hard, or if your vehicle
receives an impact of 5 mph (8 km/h) or more,
the safety belt will become locked and help
reduce your forward movement.
To unfasten all the belts:
1. Push the release button on the end of the
buckle. This allows the tongue to unlatch
from the buckle.
Unfastening the front outboard lap/shoulder belts
Unfastening the rear outboard lap/shoulder belts
116