Gravity Ventilator Fan Size 20 In Width 35 1/2 In Depth 35 1/2 In Overall Height 13 In Base Width 30 In Base Length 30 In 1226/545 CFM/Throat Velocity @ 0.050-In SP Gravity Intake 1435/638 CFM/Throat Velocity @ 0.050-In SP Gravity Relief Max Intake CFM/Throat Velocity 2658/1188 Construction Spun Aluminum