JM Mineral wool Curtainwall Insulation is made of inorganic fibers derived from basalt, a volcanic rock. Advanced manufacturing technology ensures consistent product quality, with high-fiber density and low shot content for excellent performance. Mineral wool Curtainwall is available in plain or faced with a (FSP) Scrim Reinforced Foil Facing vapor retarder on one face. Mineral wool Curtainwall is inorganic, noncombustible, moisture resistant, non-deteriorating, and will not mildew or support corrosion.