Types 0110DOW, 0120DOW, 0110GOW and 0120GOW are "out of wall or flooring" integral sleeve static curtain type fire dampers.  Product 0110GOW and 0120GOW are especially designed for offer or return ducts that terminate in a grille or sign-up. Model 0110DOW and 0120DOW are made for as a result of penetrations https://archerlbqdq.theisblog.com/37291644/dampers-for-industrial-sector-fundamentals-explained