An example of a blockhouse type Dd, armed with two 25 mm AT guns and two light machine guns. This type was a design by the engineers corps in Lille. In most sectors of the Maginot Line the construction of the light blockhouses by the field troops was hardly coordinated. However Lille was a good exception. The engineers made a total of 25 standard designs, armed with 25 mm guns and LMGs. The standardisation made the production of doors and embrasures much easier and also allowed the engineers to construct a large number of these blockhouses.