This is a replacement roller brush assembly for all Eureka The Boss Smart Vac 4870 Series Upright Bagged Vacuum Cleaners. This brush, also called a beater bar, or brush roll includes all components, including both the left and right plastic end caps, ball bearings, and the brush core and bristles, fully assembled and ready to install. The end caps on this brush are an Hexagon Shape, and the brush measures approximately 14 3/8" long, with 1 1/3 in. to the right of the belt pulley. Used with the Eureka Style R Belt (part 61110 sold separately) this brush is more prone to damage then other Eureka Brush Rollers. To prolong the life of your roller brush, it's recommended to remove both plastic end caps once every 30 days, and clear and debris such as thread, or hair which may be wrapped around the bearings, and while you have the bearings exposed, put some bearing grease on it to keep it spinning smoothly. Fits Eureka Part 61250-3, and The Boss Smart Vac, and Omega Models; 4870AT, 4870ATV, 4870BT, 4870DT, 4872AT, 4872BT, 4874AT, 4880AT, 4885BT, and 4885AT.