Large, low profile, round static roof mount attic exhaust ventilator. Galvanized steel construction. Suitable for up to 8/12 roof pitch. Includes galvanized steel mesh grill to protect against insects, birds, and rodents, yet allows adequate air intake. Moves 28% more air than a wind turbine. Easy installation with no special tools required. 163 sq in (square inch) Net Free Area (NFA). 26" diameter dome. Base: 25" x 25". Opening: 15" diameter. Requires adequate soffit intake vents. WARNING: This product can expose you to chemicals including Chromium which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information visit www.P65Warnings.ca.gov - Nickel (Metallic)