This was the TM Tourelle and contains a 50mm mortar. The mortar was know as the Mortar 50 mm Modéle 1935 and it was built for fortification use in the TM Tourelle and GFM Cloche. It was breech loaded and the design began in 1931 after an important need! But only in 1935, the factory of Manufacturer Châtellerault (or MAC) present his first prototype. It was nearly the same design like the German 50mm MGrW M19.
The stationary turrets of Maginot Line can be raised or lowered using arrow keys. Note that the exposed armour of raised turret is very thin.