Extremely useful for those who drill a lot. After making hundreds of holes, the drill bit is not as sharp as it was originally. However, do not throw it away, because you can prolong its life with the help of sharpening. And to sharpen it will help the same drill that dulled the drill bit. A special nozzle with a sharpening corundum stone is put on the drill and allows you to sharpen drill bits carefully and safely. The drill bit is fed at the right angle on a plastic guide, so it is very difficult to spoil it. The drill bit is 185 mm long and 40 mm wide.