Designs 0110DOW, 0120DOW, 0110GOW and 0120GOW are "out of wall or flooring" integral sleeve static curtain kind fire dampers.  Product 0110GOW and 0120GOW are exclusively created for offer or return ducts that terminate at a grille or sign up. Model 0110DOW and 0120DOW are designed for via penetrations (ductwork linked https://heavydutystainlesssteelda46788.madmouseblog.com/17628807/dampers-for-industrial-sector-an-overview