Model D0110DOW, D0120DOW, D0110GOW, D0120GOW are "out of wall or ground" integral sleeve dynamic curtain kind hearth dampers. Design D0110GOW and D0120GOW are designed for provide or return ducts that terminate in a grille or sign up. Model D0110DOW and D0120DOW are created for by penetrations (ductwork linked to either side) https://caidenhynap.verybigblog.com/35943747/examine-this-report-on-heavy-duty-stainless-steel-damper-manufacturers