Fibrous glass duct insulation means proven performance. These products are manufactured to meet exacting physical property and performance requirements set forth in ASTM, UL, and NFPA standards and test procedures. The design, fabrication, and installation of air duct systems insulated with fibrous glass are all accomplished by skilled, trained contractors supported by comprehensive industry standards, including NAIMA's "Work Smart" program which covers recommended practices for the handling and installation of all kinds of fibrous glass insulation products.