Model D0110DOW, D0120DOW, D0110GOW, D0120GOW are "outside of wall or flooring" integral sleeve dynamic curtain variety hearth dampers. Design D0110GOW and D0120GOW are made for source or return ducts that terminate in a grille or sign-up. Product D0110DOW and D0120DOW are made for by means of penetrations (ductwork linked to each https://dampersforindustrialsecto90012.dm-blog.com/37034379/dampers-for-industrial-sector-for-dummies