Designs 0110DOW, 0120DOW, 0110GOW and 0120GOW are "out of wall or flooring" integral sleeve static curtain form hearth dampers.  Design 0110GOW and 0120GOW are specifically made for source or return ducts that terminate at a grille or sign up. Model 0110DOW and 0120DOW are suitable for through penetrations (ductwork linked https://dampers-for-industrial-se34556.bloginder.com/37756309/the-basic-principles-of-dampers-for-industrial-sector