Atlas EnergyShield Ply Pro is a high-performance thermal insulation board composed of a closed cell polyisocyanurate foam core patented glass-mat facers bonded to 5/8" or 3/4" fire retardant treated plywood. It is manufactured using environmentally responsible processes and formulations, containing no CFCs, HCFCs or HFCs, resulting in Zero Ozone Depletion Potential (ODP) and Negligible Global Warming Potential (GWP). Boards are available in sizes 4' x 8' and foam thickness from 1" - 4".