X 25 Ft. Aluminum Foil Fiberglass Insulation Radiant Barrier for Outdoor/Indoor Freezing Weather, Thickness 2 In. Insulation Type Radiant Barrier. Noise reduction: safe sound absorption noise The material of glass wool roll felt is glass fiber, the core material is glass wool, the thermal conductivity (normal temperature) is 0.035, the use temperature is 350, mainly used for pipeline insulation.