aluminium foil insulation (facing) is an economical duct wrap and radiant heat insulation. FSK(foil-scrim-kraft) Facing is intended for use as an attic, roof, or wall radiant barrier and as a class A insulation facing to block radient heat coming into house through the roof and wall during summer and retain indoor heat generated during winter. Also used as a moisture vapor barrier in air conditioning ductworks and cold rooms.Aluminum foil insulation provides an efficient, space saving.