This magazine is unmarked and of very bad quality (double weld spots). The shape of the weld spots indicate Mauser production. Only a serial number is applied on the spine by an electric pencil, indicating that the magazine was used postwar by the Czech army.
My opinion about this magazine is that it was produced in the last days of the war. During this time stamping and inspection was probably not a priority anymore and the only thing that counted was to produce weapons for the German army as fast as possible.
The magazine has a ribbed follower which also indicates late war production. This magazine is the only one of this variation that I have seen so far.