SilverSark xR is an extra R-value insulation, which increases the total R-value in walls up to R.05 compared to single-sided foil sarking. It is an extra heavy duty, double-sided reflective foil insulation and radiant barrier with a Class 2 Vapour Barrier. There is an anti-glare coating on one side of the insulation for easy installation and is puncture resistant. SilverSark xR is ideal for steel or timber framed, tile, and metal roofs in residential, commercial, and office buildings.