Amazon.com - 2-Pack Dual Model Virtual Wall Barrier Compatible with iRobot Roomba 500/600/700/800/900/e/i/s Series Robot Vacuum. Compare to Part 4636429 -
Amazon.com: iRobot Roomba Authentic Replacement Parts - Dual Mode Virtual Wall Barrier (2-Pack) : Home & Kitchen
Amazon.com - iRobot Roomba Authentic Replacement Parts - Dual Mode Virtual Wall Barrier Compatible with Roomba 600 700 800 900 Series -