So I actually bought this pack because I needed a replacement rotary brush for the side of my vacuum. The package is generally excellent, you get a range of bags, filters, brushes and the same reels for the main brush. My only complaint is with the main brushes. So I replaced my main brushes and now my robot gets stuck all the time, it says the brushes are clogged and need cleaning. In addition, when working when turning, there is a terrible grinding noise. I noticed that the main brushes that came in the box have longer ends on the 'brush part', I don't know how to explain this as it's all plastic anyway. So I assumed this is what they look like when new as mine is almost a year old now. In any case, I think that the vacuum cleaner has problems with the rotation of the main brushes because they are too stiff. The factory ones are a bit softer and bend more easily. . These new ones seem to be made out of harder plastic and when my vacuum is running it tends to stop and tell me the main brushes are clogged. Anyway, I got my old brushes back and they work perfectly. I suppose if I bought replacement knees for the main brushes I'd be more upset, but I don't really need them because my factory brushes work just fine. The rest of this pack really is steel considering a replacement brush from iRobot costs $34.