This machine will take a knife from sharp to a level of sharpness that is beyond how sharp the knife was when it was new out of the box. The quality is top-notch. When using it you can tell you are using a quality knife sharpener. OK, now for the reason for 4 stars.
After unpacking the knife sharpener, and reading all the literature that came with it, I was excited to try it out for the first time. I inserted the depth key, placed a knife into the jaws, using the supplied Allen key to lock the jaws down onto the blade. When removing the depth key, it came out with only one prong on it, with the other one left inside the jaws. This may seem like a trivial issue, but I can't help but feel that when you spend $400.00 dollars on a knife sharpener, something as important as the depth key would be made with the same quality as the rest of the machine. Maybe the prongs should be made from steel so this would be avoided. I have not contacted customer service because to me it's not worth the hassle. I'm just going to make one myself which I know won't break upon first use. Other than that, this is one great machine.