"Before we made sharp things, we made things sharp." is a tagline that
Spyderco uses in the advertising of their knife sharpening called the
Sharpmaker. It is true, the first product Spyderco released was a knife sharpening system and not the very popular folding knives that we know them for today.
The Sharpmaker is composed of two triangular (cross section wise) sharpening stones and brass rods. These sharpening stones fit into slots in the handy carrying case which lets it stand at an angle. These angles are the prescribed sharpening angle for creating either a single or double bevel on the edge of your knife or other sharp object. The brass rods act as guides or rather guards to keep you from accidentally cutting yourself while sharpening. Because of the downward motion required to sharpen the knives, some people claim they can better maintain the required angle for sharpening the blade.
It is a popular sharpening system for people who have many knives and also can be used as a field sharpening system.