The cover is woven with Owens-Corning Fiberglass yarn and is guaranteed never to burn. It is a weave used for fire fighters, racecar drivers and astronaut's protective clothing. It reflects approximately 95% of the heat placed on it, making it possible to with a MEDIUM heat setting (either steam or dry) to iron all fabric-linen, cotton, silk, wool and synthetics. Place buttons, snaps, zippers, needlework, and fabric with nap right side down and iron on the backside. The nap, hardware or needlework sinks into the super cushion allowing the iron to glide easily, and perfectly iron both sides at once.