In 97% condition, we have one of the more obscure German Pocket pistols of the post WWI era, the Model 1920 Rheinmetall Pistol. Only around 12,000 of this model were manufactured before the collapse of the company due to the hyperinflation of the Weimar era. This is a textbook 100% factory original example that was probably made in 1923. Almost certainly a WWII vet bring back.
Interesting fact about this model of pistol is that it was the model that replaced the 1907 Dreyse Pistol that was also manufactured by Rheinmetall. While commercially in-successful it certainly was a much more effective design than the Dreyse.