French EFA T-21 (Etudes et Fabrications Aeronautiques), used by Swiss Mirage III S pilots on high-altitude interception missions.
This equipment was declared obsolete when the Mirage III S was phased out in 1999.
The soft EFA helmet bag was stored in the typical heavy "Sportex" cardboard carrying box.
Remains of stamps and addresses of Swiss AF bases on the box cover are giving evidence of helmets being shipped by ordinary mail. (!)