a composite insulating material which is comprised of one or more layers of open ended cells formed from flexible thin plastic sheet , and may be fastened to one or more cover sheets . the material is flexible enough to be worn as clothing and derives its insulating properties by reducing thermal conducting paths and areas , by introducing numerous controlled geometry air cells between the heat source and inner layer to further lower conductivity and inhibit convection currents and , by absorbing radiant thermal energy within the cell walls thereby reducing heat transmission by radiation . metallized reflecting layers are not required to achieve high insulating efficiency .