Hi,
XII. 1. means saxon 1. Landsturm-Infanterie-Bataillon Dresden, and I think the 45 has something to do with the 1. sächs. Infanterie-Brigade Nr. 45, also based in Dresden. Early in the war the Landsturm troops wore their Infanterie-Brigade number on the collar, maybe it was moved to the helmet when the army corps / batallion system was introduced?
Regards,
Lars