Model # YWF6E400-BExtra High Speed Exhaust Fan 1,500 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.Blase Diameter 16"Framing Dimension 20" x 20"Efficient, low maintenance, easy to install