Fi-Foil’s Silver Shield is intended for use on the underside of roof rafters with a perforated radiant barrier to allow for vapor transmission. Silver Shield is a multi-layer radiant barrier with a metalized PVC inside layer. The outer layer is made from .000285” aluminum foil reinforced with a tri-directional fiberglass and polyester scrip and laminated with a fire retardant adhesive to 30 lb. natural kraft.