Pre-insulated ducts and fittings, intended for both indoor and outdoor use. The system is based on sheet steel inner and outer casings with insulation in between.
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The nominal size ø 100-500 always refers to the inner duct diameter, irrespective of the type in question. There are two types to choose from, type 25 and type 50.
Due to different norms and regulations the program can differ a bit between countries.