Chevrolet 2004 Malibu Owner's Manual page 114

Upper Position
2-46
1. To use the panel in the upper position, insert the
front corners of the panel into the top guides and
slide the panel forward. Press down on the back of
the panel to lock it in place. This can be used as
a cargo cover for the rear area. The panel may be
installed either carpet or plastic side up. On the
rear edge of the panel are four grocery bag hooks
for your convenience.
CAUTION:
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If you were to carry things on the adjustable
panel when it is in the upper (cargo cover)
position, then during a sudden vehicle
movement or a crash those things could be
thrown around in the vehicle. You or others
could be injured. When it is in the upper
position, always secure any cargo on the floor
beneath the panel/cover.