Models 0110DOW, 0120DOW, 0110GOW and 0120GOW are "from wall or ground" integral sleeve static curtain kind fire dampers.  Design 0110GOW and 0120GOW are particularly created for source or return ducts that terminate at a grille or register. Design 0110DOW and 0120DOW are created for through penetrations (ductwork connected to both https://dampers-for-industrial-se45667.dailyhitblog.com/42483559/details-fiction-and-dampers-for-industrial-sector