single date 1920 value/where it came from?

[Don M]

Originally Posted by Geo99

I have not seen those particular inspector proofs before - does anyone know what they are?

Those are the stamps of the Ausrüstungsamt (government procurement office) ArA4 which was formed after WWI. In 1921, it was renamed Waffenamt 4 and the stamps were replaced with an eagle over WaA4. They were used only for a short period of time and, to my knowledge, used only on 1920 and some 1921 dated DWM P08s.