Replacement Filter and Brush for iRobot Roomba 550 Series Product Specifications: Package contains 1 Side Brush & 1 Filter For use with iRobot Roomba 550 Series Vacuum Cleaning Robots. Changing filter every 2 - 3 months recommended. Remove dustbin and slide filter out to clean or change. Filters maintain optimal cleaning performance. Filters reduce infiltration of dust, pollen and other allergens. Prevents dust and dirt from escaping vacuum system. It"s best to replace your brushes every 1 to 2 months which will bring your Roomba back to top cleaning performance This Product works in or replaces the following OEM model numbers: 20938 53601 55101 iRobot Roomba 550 Series Vacuum Cleaning Robots. iRobot Roomba 536 iRobot Roomba 551 iRobot Roomba 50