This Exhaust Fan is great for industrial environments providing extremely high RPM. Exhaust fan is made with heavy gauge welded venturi framing and precision balanced fan blades. Features belt driven, totally enclosed ball bearing motors for long life. V-belt drive provides quiet operation. Pre-lubricated sealed bearings are within ball bearing self aligning pillow blocks. Totally enclosed motor. Three phase design. Assembled. Horsepower rating based upon maximum speed/load.