Mule-Hide Poly ISO Flat insulations consist of a closed-cell polyisocyanurate foam core laminated to heavy, (non-asphaltic) glass fiber reinforced felt facers. The product insulations are compatible with all Mule-Hide membranes and accessories and are available in 20 and 25 psi densities. Mule-Hide Poly ISO insulation boards may be used for ballasted, mechanically attached and fully adhered single-ply roofing systems. Poly ISO insulation board may be installed over approved decks and substrates on new construction, tearoffs and recover (retrofit) projects. Rated for use in UL Class A and FM Class 1 assemblies.