EK2 Iron Cross so called “LUG” with marked “Z”

this piece is included in Dietrich Maerz new EK2 book on page 508.

The maker unknown .In general, these pieces are unmarked, but on this the piece ,on the ring have marked mark Z .
There are two seed versions for this cross type, this is the 1 version..Although the maker is unknown, but in my opinion there is a possible Juncker connection between the pieces, since on this the piece a same marking “Z” can be found in very rare