A blanket-type insulation composed of glass fibers bonded together with a thermosetting resin. Available with either a FSK or vinyl-film vapor retarder facing. FSK is a glass-scrim reinforced laminate of aluminum foil and kraft paper bonded together with a flame-retardant adhesive. The vinyl film is available in two colors: white or gray. It is used to insulate rectangular and round heating, ventilating, and air conditioning ductwork that supplies conditioned air at temperatures from 35°F to 250°F for faced duct wrap and from 35°F to 350°F for unfaced duct wrap. Helps control heat loss or gain and condensation during system operation.