Exhaust Fan Control Type Rotary Dial Duct Diameter 8 in Exhaust Airflow @ 0.000 in SP 180 cfm For Maximum Wall Thickness 9 1/2 in For Minimum Wall Thickness 4 1/2 in Housing Material Steel Housing Finish Galvanized Includes Backdraft Damper Rotary On-Off Switch Weather Hood Maximum Airflow 200 cfm Maximum Coverage Area 195 sq ft Maximum Noise Level 9 sones