7.75 inH 21 inL 8 inW Motrzd Fire/Smoke Damper For Nominal Duct Diameter Not Applicable Damper Application Fire and Smoke Number of Panels 1 Overall Height 7 3/4 in Overall Length 21 in Rough Opening Shape Square For Duct Shape Square Overall Width 8 in Frame Material Thickness 16 ga Blade Material Galvanized Steel Maximum Air Pressure 4 in wg Overall Diameter Not Applicable Rough Opening Width 8 in Damper Type Dynamic Maximum Air Velocity 2000 fpm Nameplate Voltage 24V DC