It is a special gadget. It was designed by Ron Hood, and works pretty well for Ron Hood, despite the obviously cut fingers in the picture from where they encountered the back of the blade. It is in the same category as the Tracker knife, designed by Tom Brown for Tom Brown. Both get sold on the strength of their reputations and are probably taught to their students. Both are very expensive, and both are hard to find due to the limited production. Both come with manuals on how to use them. If you know how to sharpen your knife, you shouldn't need a manual to maintain and use your knife IMO.

One of the few knives like this I've seen that don't leave me cold is the Pathfinder from Dave Cantebury. That looks to be pretty much idiot proof- it is a mini kukri type blade with a bit of saw tooth on the spine for making notches. But generally, I'd rather have a good, simple knife, and either a SAK or a multi with a saw blade for making the notches and to have as a back up blade.