I have never seen anything like this before?
Peter, where are the cockades? Where are the front and back?
If it were from a garde regiment wouldn't it need a KBAG or BAG mark then? BA II would just be standard army korps mark.It could also be a cap of the „Garde-Maschinengewehr-Abteilung Nr. 2“ (Greygreen cap with black stripe and red lines), which was assigned to the 2nd Battalion of the Garde-Grenadier-Regiment No. 4.