This is the most user-friendly sharpener Øyo has had in more than 100 years of knife manufacturing. You cannot make mistakes. The sharpening steel is made of tungsten with a diamond grain, which means the sharpener has a long service life. To fit most European knives, the sharpening steel is set to a 20 degree angle. There is a simple instruction manual with the product. It takes up minimal space in the kitchen drawer, and is lightweight and easy to take with you. Can only be used on steel knives.