Beginning in the late 1930s, the French part of the Waterman company made a pen that utilizes a glass cartridge. The model pictured here is the streamlined version from post WWII. The glass cartridge has a small stopper in the neck, which is pushed into the vial when the cartridge is tightened into place by the rear cap. There is also a spring mechanism in the end of the blind cap to better hold the glass cartridge firmly in place. The feed extends into the cartridge neck, but is loose fitting. The seal is accomplished by a rubber seal around the outside of the flange of the cartridge.