TOYOTA 2011 Tundra - Manual (Page 494)

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3-7. Using the storage features
Rear door (type A)
Rear door (type B)
n Removing the hold separator (front bench type seat only)
CAUTION
n When not in use (front bench type seat only)
Keep the bottle holders closed.
Injuries may result in the event of an accident or sudden braking.
Remove the hold separator.
Bottle holders