The Roomba virtual wall technology utilizes an infrared beam of light to keep the Roomba Robot from passing into other rooms. This technology has been present since the original Roomba Series. With the 3rd generation Roomba (500 series) iRobot introduced a method to contain Roomba (using a virtual wall) to finish cleaning one room, then be directed into the next room to clean. This allows Roomba to stay and efficiently clean a smaller area before going to tackle the next cleaning room.
Note: Roomba 510 and Roomba 530 models are not compatible with the Virtual Wall Lighthouse technology. Requires 2 'C' Size Batteries.