Chevrolet 2006 Avalanche Owner's Manual page 32

The lap part of the belt should be worn low and snug on
the hips, just touching the thighs. In a crash, this applies
force to the strong pelvic bones. And you would be less
likely to slide under the lap belt. If you slid under it, the
belt would apply force at your abdomen. This could cause
serious or even fatal injuries. The shoulder belt should go
over the shoulder and across the chest. These parts of
the body are best able to take belt restraining forces.
The safety belt locks if there is a sudden stop or a crash,
or if you pull the belt very quickly out of the retractor.
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