I tried using it once, but it wasn't necessary for my home, so I put it away. ● A convenient optional item that can restrict the operating area of a Roomba. ● It creates an invisible wall with infrared rays, allowing you to divide rooms. It's useful when you want to keep the Roomba out of certain spaces or when using it in part of a barrier-free room. Size: 10.5 x 8.5 x 4.5 cm Uses 2 size D batteries. Batteries are not included.