Rmax R-Matte® Plus-3 is an energy-efficient thermal insulation board composed of a closed-cell polyisocyanurate (polyiso) foam core bonded to reinforced aluminum foil facers on each side. While one side of the board has a reflective surface, the other side has been coated to have a non-reflective white matte surface. Boards can be installed with either the silver or white side out. For additional radiant barrier properties, install silver side against air space if one exists. This thermal insulation is designed for use in cavity walls, masonry walls, vaulted ceilings and many other building envelope continuous insulation applications.