Styles 0110DOW, 0120DOW, 0110GOW and 0120GOW are "out of wall or flooring" integral sleeve static curtain style fire dampers.  Design 0110GOW and 0120GOW are specifically made for offer or return ducts that terminate in a grille or sign up. Model 0110DOW and 0120DOW are made for as a result of https://paxtonyqfti.shoutmyblog.com/36090103/about-heavy-duty-stainless-steel-damper-manufacturers