Model D0110DOW, D0120DOW, D0110GOW, D0120GOW are "away from wall or flooring" integral sleeve dynamic curtain type fireplace dampers. Model D0110GOW and D0120GOW are suitable for source or return ducts that terminate in a grille or register. Model D0110DOW and D0120DOW are made for via penetrations (ductwork linked to either side) where https://felixtixky.topbloghub.com/43410241/everything-about-dampers-for-industrial-sector