Models 0110DOW, 0110GOW and 0120GOW are "out of wall or floor" integral sleeve static curtain type fire dampers.  Model 0110GOW and 0120GOW are specifically designed for supply or return ducts that terminate at a grille or register. Model 0110DOW is designed for through penetrations (ductwork connected to both sides) where the damper cannot be installed within the plane of the wall. For use where local building codes require the protection of HVAC ductwork penetrations in walls, partitions or floors that have a fire resistance rating of up to 2 hours. These dampers are classified for use only in static "fans off" systems where the HVAC system is automatically shut down in the event of a fire alarm. These models are particularly suited for use in common steel stud drywall partition designs, as narrow as 3 1/2" (89) where a traditional "within the plane of the wall" fire damper installation is not possible.