Knife sharpening is as old als the history of the knife itself and always in discussion. There are many knife sharpeners, but none of them is really convincing. Professional as well as private users often complain: Too complicated, patience when using it, results not satisfying, marks on the blade, not suited for all knives, much too expensive etc." Harald Stallegger, Boker retailer from Salzburg has thoroughly studied sharpening techniques and has developed an outstanding system which he also has patented. The Vulkanus Knife Sharpener. The solution of the problem: Spring-cushioned bars of hard alloys (with carbon-reinforced polyamides) which stay firmly in contact to blades of any shape. Two different angles between blade and sharpening bars provide two levels of sharpening. 1, sharpening of the blade by removing considerable amount of material (knife tip pointing downwards when drawing through) and 2, honing (removing the burs) of the edge with the tip pointing upward when pulling through. The result will be perfect. Also people who are untrained in sharpening will get razor sharp blades within a few minutes. Both for knives with plain edge and with serrations.