Hummer 2004 H2 - Manual (Page 128)

If your vehicle has a sunroof, it will have a crossrail stop
tab placed in the siderail in the spot labeled SUN—ROOF
STOP. This tab prevents you from moving the crossrails
past the opening of the sunroof and loading cargo too far
forward.
Your vehicle will also have a stop tab in the crossrail in
the spot labeled ON STAR STOP. This tab prevents
loading cargo too close to the OnStar antenna which will
cause the OnStar and navigation system (if equipped)
to function improperly or not at all.
Vehicles with the off-road lamps will have additional
stop tabs placed in the siderails to prevent you
from moving the lamps too far rearward, causing them
to shine into the optional sunroof opening.
Crossrail Channels
Notice: If you drive your vehicle through an
automatic car wash that does not have enough
clearance for any roof-mounted accessories (such
as off-road lamps or a roof basket) on your vehicle,
you can damage your vehicle. To avoid damaging
your vehicle in a car wash, remove any
roof-mounted accessories if you can, and do not
use an automatic car wash while roof-mounted
accessories are on your vehicle. See Cleaning the
Outside of Your Vehicle on page 5-95 for more
information.
The crossrails have built in channels to allow you to
attach other items designed for this system, such
as basket luggage carriers, bike racks, ski racks, etc.
To use the crossrail channels, do the following:
1. Use the included key to unlock the crossrail end
cap by turning it counterclockwise. If you ever
loose a key, your dealer will be able to help you
obtain a replacement.
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