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There is a single "box" you can use to setup a barrier. The box has two modes. You can use the straight line mode to block off a doorway. It will setup an barrier to between it and the wall across from it that the Roomba won't cross. There is also an "arc" mode that you can use by let's say placing it between your dog bowls. That will create an arc around the bowls so it won't repeatedly ram into them. Otherwise, it has free reign of where it will go. If the battery starts getting low, it will return to base.