Fibrous glass duct wrap insulation is designed for application to the exteriors of commercial and residential sheet metal heating, ventilating, and air-conditioning ducts and plenums operating at temperatures between 40˚F (4˚C) and 250˚F (121˚C). Duct wrap insulation reduces heat loss or gain through duct walls, conserving energy and controlling moisture condensation. Fibrous glass duct wrap insulations are useful in situations where acoustical performance is not an issue.