These marks and stickers were found on a series of female wall masks. Various sources claimed that they were produced between the 1920s and 1940s.
There is another unidentified mark containing the name "Brandl", please see M160820.

M160811a
Impressed "NKZ" above "BRANDL" and "ČECHOSLOVAKIA".

M160811b
Impressed "NKZ" above "BRANDL" plus a second "BRANDL".

M160811c
Ink stamped "NKZ" above "BRANDL".

M160811d
Circular sticker showing "NKZ" above "BRANDL".