This is a listing for one iRobot Dual Virtual Wall. It came with the iRobot I purchased, but I am selling it separately because the main unit broke. Please check the photos for scratches. The virtual wall that prevents Roomba from entering has evolved to be even more convenient. It creates an invisible infrared wall in places where you want to restrict Roomba's entry, such as doorways without steps. You can also avoid areas like pet water bowls with the "Halo Mode," which creates a circular no-entry zone. An accessory for robot vacuums equipped with obstacle avoidance sensors. - Brand: iRobot - Model Name: Robot Vacuum Accessory - Features: Equipped with obstacle avoidance sensor - Color: Black - Size: 2.1ft/0.6m