Model # YWF4E300-BExtra High Speed Exhaust Fan 950 CFM. Exhaust Out.Totally enclosed motor with auto overload protection. Outside rotor motor for higher efficiency.Strong powder coated OSHA guard.Black powder coat maintenance free durable steel construction with outside rotor motor for high efficiency.Swept back high efficiency low noise blade design.Framing Dimension 16" x 16"Efficient, low maintenance, easy to install