Model 0540V Wide Frame Static Curtain Fire Damper is UL approved for use where building codes require the protection of HVAC ductwork penetrations in vertical fire separations (walls or partitions) that have a fire resistant rating of 4 hours or less. The 0540 is classified for use in static "fans off" systems where the HVAC system is automatically shut down in the event of a fire and is ideal for applications where maximum free area is desired, in situations where space or design does not yield room for a Type B damper style. The design includes corrosion resistant steel frame and blades for lasting performance and is available with factory installed sleeve for fast and simple installation.