This is in regard to HRV or Range hood ducting to out side with galvanized.

Its gets to -40 celsius here.

I have seen reflexive and foil back, one company recommended gutting flex to slide over galvanized.

Just wondering what the more commonly used type is.

The R values seem low but possibly thats enought to stop condensation? I have seen pics rotted sections of foil back... possible due to condensate getting in the pink.