The Virtual Wall uses an infrared beam, preset for 4 to 7 feet, to block Roomba from doorways, stairs and other off-limit areas where it can be damaged or do damage. Its small profile keeps the unit unobtrusive and allows for use nearly anywhere your require. Compatible with the Roomba 500 series, including the Roomba 510 and Roomba 532 Pet Series Robot Vacuums. This unit is automatic, meaning you never have to remember to turn it on or off! Auto Virtual Walls remain on for up to six months. Requires 2 C batteries, available separately.