Forte di Airolo had still been equipped with rotating observation turrets which were with a price of 17.000 Swiss Francs quite expensive. The newer generation of works got fixed turrets which costed only 4.200 Swiss Frances. The armour of these turrets ranged from 100 mm at the roof to 200 mm around the observation slits. They weighted around 7 tons. This was one installed at the Ouvrage de l'Hospice near the St. Gotthard pass.