Design D0110DOW, D0120DOW, D0110GOW, D0120GOW are "out of wall or floor" integral sleeve dynamic curtain variety fire dampers. Product D0110GOW and D0120GOW are created for supply or return ducts that terminate in a grille or register. Product D0110DOW and D0120DOW are created for as a result of penetrations (ductwork linked to https://heavydutystainlesssteelda12346.blogsumer.com/35984330/dampers-for-industrial-sector-for-dummies