Specification HTM Series is a flexible, high-performance, silica aerogel-based insulation material of limited combustibility used for exterior and interior applications. Description: HTM Series is a flexible, high-performance, silica aerogel-based insulation material of limited combustibility used for exterior and interior applications. Supplied in a variety of finishes, the substantial layers of HTM Series meet the requirements for A2 classification (insulation, MgO and plasterboard, and anything you wanted).  The product is used to optimize the thermal performance and fire properties of systems in a number of ways. These include enhancing the thermal performance of the ventilated and addressing thermal bridging in the . HTM Series is also useful in minimizing thermal bridges around windows in areas such as window reveals and roller shutter cases.