Mule-Hide Poly ISO 1-HD80 is a ½" thick, high-density polyisocyanurate insulation board that was specifically designed for use as a cover board with mechanically attached and induction welded single-ply roofing systems only. Suitable for use with approved fasteners and plates. This product consists of a closed-cell polyisocyanurate foam. In addition to providing a durable underlayment for roofing membranes, Poly ISO 1-HD80 has an R-value of 2.5 which is significantly higher than that of other cover board products such as wood fiber or gypsum.