US WW2 Armor flyers apron M-4 Flak vest

M-4 Armor flyers apron for the M-1 and M-2 protective vest to protect the private parts during heavy flak. As used by B-17  and B-24 bomber personnel, C-47 pilots, Glider pilots etc. Hard to find on the loose. Heavy piece! Came out of an old collection which was accumulated around the Nijmegen area.