The name of the material-«Cellular polycarbonate»-is due to its internal structure, which resembles the structure of bee cells. In most cases, sheets of this material are made up of two (or more) parallel thin plates and the partitions connecting them. Inner voids formed by plates and partitions are filled with air, which gives cellular polycarbonate high thermal insulating properties. Such elements of the structure of the material as stiffener ribs provide sufficient constructive strength of the sheet with slight weight.