Good stone to sharpen his knives, there are always better, but in this case it is much more expensive! Its dual weight 1000/3000 allows to "repair" the thread of a worn knife as maintain those intersect. Sharpening a knife is an operation that can be quite long, no magical operation which takes 2 or 3 minutes. It takes 15-20 minutes more in some cases to give (or give) a decent edge of a razor. Attention to the angle when sharpening a knife ... all knives do not have the same angle! Between 15 ° and 25 ° depending on the knives and their use. The easiest way is to look on Youtube, there are no tutorials for appendre. And before embarking on sharpening a knife "high end", to experiment on any knife to take good gesture.