Opel INSIGNIA Owner's Manual page 77

Installation of hooks in the rails
Insert the hook in the desired position
first into the upper groove of the rail
and then press into the lower groove.
To remove, first pull out of the upper
groove.
Service box
Install two hooks in the upper rail.
Insert the upper brackets of the box
from above into the hooks.
Storage
Alternatively install both hooks in the
lower rail. Plug in the lower brackets
of the box from above into the lower
hooks.
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