When the bag becomes full

filters should be replaced every 2-3 months

a top-fill Advance Filtration disposable inner bag zips into a heavy-duty cloth bag

Perforated steel intake housing: 360° intake

iRobot Replacement Bristle Brush (3-pack) for Red or Green Cleaning Heads Hoover Brush Bars When the bag becomes full[custom_html] Replacement bristle brush pack shown here is for iRobot Roomba 500 and 600 series vacuum cleaning robots with red or green cleaning heads. iRobot recommends cleaning your Roombas brushes every 1 to 3 uses and replacing them depending on the amount of dirt and debris in your home. [ custom_html]