Over-foil 311 is a reflective insulation foil in rolls with absolutely unique performance characteristics that cannot be compared to those of other types of insulation, which depend directly on their thickness to perform their insulating function. In addition to its pure aluminium reflective surfaces, its unique feature is that it has a 3 mm thick sheet of expanded polyethylene inside and is heat-sealed in the middle and at the ends of the roll along its entire length. This special feature allows two additional insulating air gaps to be created inside the product itself during installation