The supporting structure of the armchair is made of tubular steel bar 60x60x3 equipped with holes for the insertion of the pins welded on the backrest frame and its fixing. Laser drilling ensures maximum precision. On the front face of the bar is welded the side of the armchair made of tubular steel with a rectangular section that houses the joint in pressed sheet metal with a thickness of 2 mm for the rotation of the seat. The joint is equipped with an eyelet for interlocking the seat and avoiding a possible accidental exit. At the side is also welded a 4 mm thick iron plate, bent and perforated, which acts as a seat for the armrest. On the lower face of the bar is fixed the support foot of the armchair, made with a tubular steel part with a circular section of thickness 3 mm and a diameter of 75 mm, and the part in contact with the floor in pressed sheet metal 3 mm thick equipped with three holes of diameter 11 mm, one on the front and two on the back, which serve as housing for the floor fixing screws of the armchair. The feet are present on the structure on average every 2/3 seats: this system allows you to have fewer obstacles in the floor cleaning operations, making them even faster.