Gravity Ventilator Fan Size 24 In Width 48 In Depth 48 In Overall Height 39 In Base Width 28 1/2 In Base Length 28 1/2 In 2443/536 CFM/Throat Velocity @ 0.050-In SP Gravity Intake 3591/898 CFM/Throat Velocity @ 0.100-In SP Gravity Relief Max Intake CFM/Throat Velocity 6069/1239 Damper Size 25 x 25 In. Galvanized Steel Construction