Design D0110DOW, D0120DOW, D0110GOW, D0120GOW are "outside of wall or ground" integral sleeve dynamic curtain kind fire dampers. Product D0110GOW and D0120GOW are suitable for source or return ducts that terminate in a grille or register. Product D0110DOW and D0120DOW are made for by way of penetrations (ductwork linked to both https://dampers-for-industrial-se68990.onesmablog.com/the-2-minute-rule-for-heavy-duty-stainless-steel-damper-manufacturers-77909619