a first and second sheet layer 20a and 20b with metal coatings 18a and 18b on opposite sides a carrier layer 24 preferably of cellulose fibrous fleece like material is interposed between the foils 20a and 20b the metal coatings 18a and 18b are protected by a protective varnish 22a 22b or additional layers 20c 20d fig1 shows an embossed foil 10 either with embossing pattern of fig3 as shown in area b or of fig1 or 2 as shown in area c or of fig4 b 7b as shown in area d or any of the previously described pattern according to the reflection transmittance effect desired the foil 10 is fixed to an end bar 30 which is guided in side rails 32 e g by means of rolls 34 the foil 10 is wound on a roller 36 which acts as feeding means for the foil 10 which is movable relative to a window w although the metal coated foil is flexible being formed of thin sheets of plastic coated with relatively thin layers of metal embossing of the foil increases its inherent stability the specific patterns being form stable at least substantially determines the nature of the increased stability as well as the direction of such stability thus when the foil is arranged on the exterior surface of a window and is subjected to wind forces such increase in inherent stability is of importance and contributes to the structural strength of the foil as stated previously selection of the particular pattern of embossing will enable a predetermined resolution of the reflected images as well as directional control of the reflected.