Product D0110DOW, D0120DOW, D0110GOW, D0120GOW are "out of wall or floor" integral sleeve dynamic curtain kind fire dampers. Model D0110GOW and D0120GOW are made for source or return ducts that terminate in a grille or register. Model D0110DOW and D0120DOW are suitable for by way of penetrations (ductwork linked to either https://dampersforindustrialsecto25678.mdkblog.com/43001642/dampers-for-industrial-sector-fundamentals-explained