MuleHide Poly ISO Flat insulation is engineered with a closed-cell polyisocyanurate foam core bonded to durable, non-asphaltic glass fiber reinforced felt facers for dependable thermal performance and strength. Compatible with all MuleHide membranes and accessories, these insulation boards are available in 20 and 25 psi compressive strengths to meet a variety of project requirements. Designed for use in ballasted, mechanically attached, and fully adhered single-ply roofing systems, Poly ISO can be installed over approved roof decks and substrates for new construction, tear-off replacements, and retrofit applications. The product is also approved for use in UL Class A and FM Class 1 roof assemblies.