The 3M™ Fire Barrier Duct Wrap 615-48 provides up to two hours of grease and air duct protection, meeting fire protection code requirements.3M Fire Barrier Duct Wrap is a flexible fire-resistant wrap consisting of an inorganic fibre blanket encapsulated with a scrim-reinforced foil. The product is 1-1/two inches thick, with 6 pcf density. It is used to fire rate commercial kitchen grease ducts as well as ventilation ducts. 3M Fire Barrier Duct Wrap 615+ is a proven alternative to 1or 2-hour fire-resistant rated shaft enclosures for grease ducts (ICC-ES ESR-1255). With its excellent insulating capabilities, low weight and thin profile, it is an ideal choice for a duct enclosure system. This non-asbestos wrap installs easily due to its high flexibility and strength