Our circular spiral ducts are used for air distribution in building ventilation systems. Manufactured from galvanised steel in a spiral-wound construction, they are compliant with standards EN 1506 and EN 12237. They provide low-leakage airflow performance when used together with compatible duct fittings. The product is approved and tested for airtightness class D systems according to EN 12237. The relevant standards are currently being revised. EN 1506 and EN 12237 are expected to be replaced by prEN 18289 “Metallic ventilation ducts – Requirements and test methods”. As part of this update, airtightness class D will transition to ATC 2 once the new standard is adopted. The ducts described in this EPD represent the company’s complete spiral‑wound product range made from galvanised steel, produced at three German manufacturing sites (Braak, Nürnberg, and Wuppertal) operating with similar technologies and materials. This range includes typical lengths, diameters from 100 mm to 1250 mm, and variants with different sheet thicknesses or optional features such as sealed folds and plastic end caps. To reflect this product group consistently, the EPD uses averaged data across all sites and variants, with only minimal variation identified between facilities. The environmental indicators are therefore presented per kilogram of product as an averaged dataset, ensuring that differences in geometry or configuration do not affect the comparability of results. Further information on our products can be found in our catalogue under https://www.rokaflex.de/katalog/