I ask your help to identify this cap.
I found it at a flea market on the desk of a seller of Swiss Army military surplus, and I liked it because reminded me the M43 field cap.
I bought it for 5 Euros, thinking of wearing it to work in the garden, but arrived home and looking more closely, I realized that the front buttons were marked on the back with the RZM and M5/102, and after a little research correspond to the manufacturer "Gebr. Gloerfeld G.m.b.H. Ludenscheid".
At this point I decided to ask your help to understand what it is.
I appreciate very much every your opinions.