Constructed from 1” thick Type 475 black mat-faced micro-air duct board 9 R-value of 4.2 Mat-faced micro-air type 475 duct boards are listed by Underwriters Laboratories as tested in systems in accordance with UL 181 Class 1– “Standard for Safety for Air Ducts”Available in 24x24 and 24x12 dimensions O.D.
