Flame Retardant, Cleanroom, Non Hygroscopic, Non Shrink, 100% Polyester.
Probably the most important question.
If you will ever be introducing supply air temperatures below the dew point of the air in the room the Fabric Ducts are installed in, then YES you will need Permeable material.
We may suggest permeable material to you for other reasons - for example if you had a short duct with a high air volume we may suggest that some of the air be allowed to permeate through the weave of the fabric.
Conversely if you have a very long duct with a small air volume we would advise that you use non permeable material (assuming the air is above the room dew point temperature) as you might lose a high percentage of your air through a permeable weave.
With Prihoda you can have a non permeable material that is machine washable and looks identical to permeable material. This is not possible with certain other manufacturers.