Hummer 2003 H2 Owner's Manual page 53

Second Row Seat Third Row Seat
4. Buckle, position and release the safety belt as
described in "Rear Seat Outside Passenger Positions"
earlier in this section. Make sure that the shoulder
belt crosses the shoulder.
To remove and store the comfort guides, squeeze the
belt edges together so that you can take them out of the
guides. Make sure you remove the comfort guide from
the belt before you fold a rear seat down.
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