Model D0110DOW, D0120DOW, D0110GOW, D0120GOW are "outside of wall or floor" integral sleeve dynamic curtain style hearth dampers. Product D0110GOW and D0120GOW are made for source or return ducts that terminate at a grille or sign up. Model D0110DOW and D0120DOW are suitable for by means of penetrations (ductwork linked to https://dampers-for-industrial-se23344.bloggosite.com/44319702/dampers-for-industrial-sector-for-dummies