Additional Virtual Wall Lighthouse.

"For use with the Professional Roomba (78138). Projects infrared beams that confine the vacuum to one room and, when the unit finishes cleaning the floor, allow it to move on to another room. Requires two C batteries. 9 1/2"" H x 3 1/2"" W x 4"" L. (4 1/2 lbs.)u000Du000Au000Du000Au000Du000Au000Du000Au000Du000A"

It is easy to buy the Additional Virtual Wall Lighthouse. online. Hammacher Schlemmer has a secure server with quick and easy checkout.