metal building materials, namely, metal structures for the purpose of modular building, wall structures, floor structures, mezzanine floor structures, elevator shafts and staircase shafts, metal frames, load-bearing sandwich structures made of metal for the purpose of frame structures, wall structures, floor structures, mezzanine floor structures, elevator shafts, staircase shafts and space modules for construction, composite panels composed primarily of metal, construction elements made of m...