The Canarm SD Series Standard Wall Exhaust Fan is a rugged, economically priced general-purpose exhaust fan available in sizes from 12" to 48". Available in single, two-speed, and variable speed models. Features a totally enclosed thermally protected motor, rugged steel welded box housing with durable powder coated finish, aluminum louver shutters supported by long-life nylon bushings (30"-48" models), and OSHA wire guards on 12"-24" models. All fans ship completely assembled. The 12"-24" models feature upgraded tie bar shutters with magnets for quieter operation and a superior seal.