One of the two cloches GFM of the work. The abbreviation GFM stands for Guetteur Fusil-Mitrailleur or Observer and light machine-gun. In fact the so-called Fusil-Mitrailleur is a mixture of a rifle and a machine-gun. It had two triggers, one for semi-automatic fire, the other for firing automatically. The turret also had a periscope in the roof for an observer.