Johns Manville - Micro-Aire® duct board is used to fabricate ducts for commercial and residential construction and delivers excellent acoustical and thermal performance. It is produced using our dedicated manufacturing process that results in increased product consistency for efficient fabrication. Micro-Aire's flexibility and design saves contractors weight and cost. In addition, installed Micro-Aire has less air leakage compared to metal ducts, which provides building occupants with more consistent temperatures, improved comfort and energy efficiency.