Your frog is somewhat unusual and deviates from the norm. Most notably are the alloy rivets used. In addition, the "V" shape of the frog stud hole is seldom seen. I have never encountered this maker/variant. However, Anthony Carter reports the manufacturer as "C POSE Wehrausrrustungen - Berlin O34, Boxhagenerstr. 16 (code "cny")". The example reported was dated 1940 and has a Carter pattern number of 310 (very common). Looking at the stitch which appears slightly worn, construction and marking, I think it is likely OK. If a repro, someone looked hard to find a very obscure manufacturer to emulate...