I'm a little confused by the many comments on matching parts. I have two 650s and these parts fit perfectly. I used an existing screw for the side spinner. I didn't even realize that screws were included with this kit and they may not fit, but the original screw fits perfectly on the spinner in this kit and no hole needs to be drilled. The spinner seems to spin well on both carpet and hard ground, although I can imagine that if it's not spinning properly it won't be able to move. As for the filter, it was easy to install. All in all it took about a minute to swap out the parts and both Roombas work perfectly. As for differences from the original parts, I would say that the bristles of the roller brush are softer than the original, and the rotating brushes are stiffer. It's not clear how these differences affect performance.