The basis of its unique construction is a 4 inch-thick wall of mineral wool insulation, shrouded with aluminum. The inner wall is microperforated to achieve higher attenuation, and the insulated baffles, also constructed with microperforated fabric, further absorb sound. A membrane of non-permeable fabric prevents the escape of any glass fibers. And full-circumference stainless steel rings sewn in to the unit provide stability. QuieTex® is lightweight and works well with fabric or metal HVAC systems.