iLIVING 18 Inch Variable Speed Shutter Exhaust Fan, Wall-MountedThe iLIVING Shutter Exhaust Fan is perfect for removing excess heat, moisture, and unpleasant odors from virtually any commercial location, including restaurants, factories, warehouses, barns, and greenhouses. This fan features aluminum blades, OSHA compliant wire guards, and automatic shutters that open and close in tandem with the operation of the fan. The completely enclosed motor is thermally protected and permanently lubricated. The fan comes fully assembled out of the box; only installation required is the electrical hardwiring. The shutter fan comes in 8 different sizes: 10 inch, 12 inch, 16 inch, 18 inch, 20 inch, 24 inch, 30 inch, and 36 inch; the 18 inch shutter fan has both a variable speed model and a single speed model. The iLIVING 30 inch and 36 inch shutter fans are only available in single speed. For variable speed models, the ILG8SC8A speed controller is sold separately.