These parts work exactly like genuine iRobot parts. Additionally, some kits do not include prop bolts. This set does. If you go to local stores like Best Buy, you'll find that such items cost almost twice as much. So this set is a very good buy. I just changed the rollers for the first time and they look exactly like the ones that came with the vacuum. I've run the robot multiple times and the Ungaro parts are just as strong as the Roomba parts.