Backdraft Damper / Wall Shutter, Fits Fan Dia. 36 in, Shutter Overall Size 39 in x 39 in, Shutter Construction Material Extruded Aluminum Frame and G-90 Galvanized Tie Rods, Shutter Opening Required 36-1/2 in x 36-1/2 in, Shutter Free Area 7.436 sq ft,…