Pontiac 2001 Montana Owner's Manual page 82

11. Now fasten the left and right halves of the
shoulder harness clip together. The purpose of
this clip is to help keep the harness positioned on
the child's shoulders.
1-70
CAUTION:
An unfastened shoulder harness clip won't help
keep the harness in place on the child's shoulders.
If the harness isn't on the child's shoulders, it
won't be able to restrain the child's upper body
in a sudden stop or crash. The child could be
seriously injured. Make sure the harness clip is
properly fastened.