The 75 mm tipo 4 was the most complicated mounting of the Vallo Alpino. The gun was mounted in a very special casemate mounting that had a very small embrasure. This was made possible by a ball in the embrasure around which the gun could move. However that's why the gun needed a large firing room. To compensate the height of the barrel the loader/gunner had a small platform to allow him to load the gun even when it was horizontal. These mountings were only used in the Batteria B3 and B4 near Bardonecchia.