There were 72 of these oval-shaped cupolas installed on the Maginot Line, all on fortifications of the New Fronts.
The cupola had an oval like shape, because both of the firing embrasures were placed at a 45 degree angle from each other, and the AM weapon required space so it could pivot easily from one embrasure to the other. An armoured plug was put into an embrasure that was not used.
Fortifications built with protection level one and two, had the model PM (petit modèle) cupola. Casemates or combat blocks with protection levels 3 and 4 were equipped with a model GM (grand modèle) cupola.