ShelterFoam GPS is a unique high-performance, closed cell, lightweight, mold and mildew resistant expanded polystyrene material used as rigid thermal insulation in the construction industry. This product has a distinct Silver-Gray color, due to the high purity graphite that is contained within the polymer intercellular substance of the foam board. The graphite particles reflect and absorb the radiant energy, which increases the insulation R-value. This bonus is obtained, while still retaining all of the performance of standard rigid insulation. ShelterFoam GPS meets or exceeds the highest standards under ASTM C578 and D6817 for expanded polystyrene, and is recognized by the ICC-ES and UL. Approved for use in certain NFPA 285 wall assembles.