MZY LLC 3 Armed Side Brush replace for irobot Roomba 800 Series 880 870 Robotic Vacuum Parts-10 Pack Compatible with iRobot Roomba 800 Series 10 pack Side Brushes for Roomba 800 Series 3 Armed 880 870 Replacement iRobot Roomba 880 3-Arm Side Brush Replace side brush every 2 to 3 months for best performance The Brush allows your Roomba to reach deeper into the carpet for a more thorough cleaning