Did this razor for a couple of months of use. Price performance is really top. However, one must also say that the Derby a wide dispersion quality are subjected. This means that some blades can be sharper than others. But it can be applied to the blade Korckentrick and feels perfect, as you can see in this video, from Minute 2:29
Simply go to YouTube you would enter / copy: "Best Safety Razor gear" -> Check of Marks.