For the restoration of heritage buildings, Optimum offers the 6500 system of thermo-insulating profiles for windows and doors. Reduced frame size, large glazed areas, excellent values of thermal and acousti c insulati on, elevated resistance, durability and light transmission, are the main characteristics of the 6500 system. It is considered a unique interpretation, using modern technology and materials of the classic metal window; all in just 46 mm of visible perimeter frame and 64 mm for the central pairing in the case of double windows. With the 6500 series, it is possible to make windows in steel, stainless steel, Cor-Ten steel, and bronze effect.