Also called "panel fans" can be used to push or pull air through any type of duct work system. Also ideal for pit ventilation. Corrosion free polyethylene housing with polypropylene blades and stainless steel hardware. Fans come in all sizes and motor combinations listed below. All motors feature totally enclosed air-over design, thermal overload protection, and double sealed, permanently lubricated ball bearings. Fan motor can be mounted in any position, vertical or horizontal. Fans run continuously, needing no shutter. A watertight variable speed controller is also available, for certain recirculation applications. CSA Approved.