11.75 inH-W 3.7 inL Square Spring Fire Dampr Damper Application Fire Frame Material Galvanized Steel Number of Panels 1 Maximum Air Velocity None Overall Height 11 3/4 in Rough Opening Diameter Not Applicable Rough Opening Shape Square Fits Fan Diameter Not Applicable For Duct Shape Square Free Area 0.6 sq ft Overall Width 11 3/4 in Frame Material Thickness 22 ga Overall Length 3 3/4 in Connection Type Not Applicable Frame Depth 3 3/4 in Rough Opening Length Not Applicable