Best Seller | DAYTON 4HX77 Damper,Backdraft 17.75 In.H-W 4.5 In.L Aluminum Backdraft Dampr, Damper Application Backdraft, For Nominal Duct Diameter Not Applicable, Frame Material Aluminum, Number of Panels 1, Maximum Air Velocity 2250 fpm, Overall Height 17 3/4 in, Rough Opening Diameter 15 1/2... ... more DAYTON 4HX77 Damper,Backdraft 17.75 In.H-W 4.5 In.L Aluminum Backdraft Dampr, Damper Application Backdraft, For Nominal Duct Diameter Not Applicable, Frame Material Aluminum, Number of Panels 1, Maximum Air Velocity 2250 fpm, Overall Height 17 3/4 in, Rough Opening Diameter 15 1/2... | | $66.89 go to store |