ERM, the larger of the two you can get. Black band around the middle
But they are fixable if you have seized ones. Pop them out with the end of the axle. Pop both plastic caps off the bearing with a small screwdriver, and scrape out any dry rubbish, and pick out the hairs. Fill with grease, and work it in until the bearing moves. Keep going! When moving well, top the grease up, put the caps back on and refit to the brushroll, and the brushroll to the machine. Fire her up a d run for a few mins and hopefully fixed!
I show it in my dc14 refurb thread if that helps, that had a seized bearing.