Model D0110DOW, D0120DOW, D0110GOW, D0120GOW are "outside of wall or flooring" 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. Design D0110DOW and D0120DOW are suitable for by way of penetrations (ductwork linked to https://heavy-duty-stainless-stee24456.blogars.com/35700407/the-heavy-duty-stainless-steel-damper-manufacturers-diaries