20", Metal Box Fan, All Metal Structure, Body, Blade & Handle, Non-Corrosive Aluminum Blades, 3 Powerful Speeds, Enclosed Motor, Stable Wide Body Frame, Top Mounted Controls, 3 Prong Grounded Plug, Indoor/Window Use Only, The Blue Plug/Patented Safety Fuse Technology, Meets OSHA Requirements, Commercial Grade, Fully assembled, ETL Listed, 1 Year Warranty.