This creates a "wall" that the Roomba won't go into. Two settings - one is a straight line, which I believe said is good for 10 ft. You can place it anywhere. The other creates roughly a 2 ft circle around the sensor. Right now, I use that in two different areas - I have 2 cats, so I place on sensor in the middle of where we put their bowls of food. That way, Roomba won't run into the bowls and spill the food. The other place is we have put up our Christmas tree (my wife loves Christmas) and with the cloth around the base, I have set one unit on each side of the tree with the 2 ft settings. It hasn't bothered the cloth at all.