iRobot Roomba Silver Dirt Detect: Roomba actually detects dirty areas and stays cleaning until the dirt is gone Patented cleaning system-roomba' powerful vacuum and counter rotating brushes reach deep into your carpet to remove dirt, dust and pet hair Bagless bin-no bags to replace; roomba's bagless bin is easy to empty and holds more dirt than ever Max mode-use max mode to clean multiple rooms in a single cleaning cycly Dirt detect: roomba actually detects dirty areas and stays cleaning until the dirt is gone