Most of the P38 pistols produced after this variation have rectangular loopholes.
The 0-Series was the first official P38 variation issued to the German army.
All parts of the 0-Series pistols are stamped with the Walther acceptance stamp E/359 and the sight is painted White/red.
The bakelite grips are black checkered and have a round loophole for the lanyard.
Varations are based on different manufacturers and changes in markings.
The Armee Pistole (army pistol) was the very first prototype/predecessor of the P38 and was already produced in 1935 by Walther in small quantities (highest serial number known is 55). Only a handfull of those pistols were produced because the German army decided to go for the more advanced P38. They are checkered and have round loopholes for the lanyard.