Special Features: Built-In Junction Box For Easy Wiring, Easy Removal And Installation Of Motor Assembly Key-Hole Mounting, Galvanized For Humid Conditions And Various Attic Temperatures, Gauge Markings For Sloan Ceiling Thickness, Includes 4" Duct Adapter, Polycarbonate Heat-Resistant Lens With U.V. Inhibitors, Precision-Balanced Impeller For Quiet Operation