Theueurmann holster designed for the High Power used by Austia after WW2.
It is made in a thick brown leather with 2 lateral external straps and a large rear flap.
It looks like it was designed for the Steyr MOD 12 but it is clearly a post 1945 Austian holster.
Some nice markings around with the maker’s name (STOLLA WIEN enroled in an oval).
This holster is explained in the book about WW2 German Military Holsters on page 77.