Produced in 1896 until 1938 by Mauser, it was sold to both civilians and the military. As a military sidearm, the pistols saw service in various wars, as well as World War I and World War II, and it's now a relic of the Old World.
It is a very rare small gun. This is the case in Fallout, but they are slightly more common in Fallout 2. One can be found in a chest at New Reno Arms, with more being possessed by guards in a special encounter. It uses 9mm ball in Fallout, with the addition of 9mm in Fallout 2. It also has a +20% to-hit because it is "extremely accurate."