"This Canarm Explosion-Proof Totally Enclosed Exhaust Fan has the quality and easy installation to make this efficient, low-maintenance fan a great choice for shops, farms and more. Depth in. 15, Dimensions L x H in. 23 1/4 x 23 1/4, Fits Opening W x H in. 21 x 21, Amps 6.6/3.3, Volts 115/230, Air Delivery CFM 3,200, HP 1/3, Needs to be Hardwired Yes, Fan Diameter in. 18, Speed RPM 1,625, Speeds qty. 1. Rugged steel welded box housing has a durable powder-coated finish Heavy wire chrome-plated OSHA guards Totally enclosed ball bearing 1/3 HP motor with thermal overload protection ensures reliable performance Installs from interior Requires hardwired connection Aluminum louver shutters are supported by long-life nylon bushings"