Miami Tech's fiberglass reducer boxes come in a variety of dimensions to best suit the needs of the job.
These boxes are made of 1-1/2" thick R6 fiberglass insulation with a foil barrier (FSK).
All models are available as pre-constructed or unfolded units.
Unfolded units can be built quick and only require tape to fasten them.
Duct openings can be easily cut with a utility knife.