Do not buy a knife cutter other than this one! I have tested many before this and it is not possible to compare. Vulcanus is even better than brown in that the angle is always accurate.
Most knife sharpeners only scratch the edge of the knife, which makes it sharp for five minutes, to soon become dull again. Vulcanus has three different grinding techniques that make the knife sharp for a long time.
Search the Vulcanus sharpener on Youtube to see how to do it. The guy who invented this is a genius.
If you regret this choice, you have not done right. Can also grind saw-toothed bread knives (if they are sharpenable).