Replacement iRobot Roomba 4200 Battery - For the iRobot Roomba 400 Series Robotic Vacuum Cleaners iRobot Roomba 4200 Battery Replacement Capacity: 3300mAh, Output Volts: 14.4V. Brand: UpStart Battery Premium Quality, One Year Warranty The Brush allows your Roomba to reach deeper into the carpet for a more thorough cleaning It's best to replace your brushes every 1 to 2 months