Replacement iRobot Roomba 4200 Battery, Side Brush and Filters Replacement - Kit Includes 1 Battery, 3 Side Brushes and 3 Filters iRobot Roomba 4200 Battery, Side Brush and Filters Replacement Kit Includes 1 Battery, 3 Side Brushes and 3 Filters Capacity: 3300mAh, Output Volts: 14.4V. Brand: UpStart Battery It's best to replace your filters and brushes every 1 to 2 months The Brush allows your Roomba to reach deeper into the carpet for a more thorough cleaning