EXHAUST FAN Guarded exhaust fans feature 120V, single-phase totally permanently lubricated motors with provisions for direct wiring. These shutter mounted fans install on inside wall and eliminate the need for external framing and shutter. Quiet operation makes it ideal for commercial environments. Aluminum blades are enclosed in a sturdy steel spiral wire guard. Note: Rough-in hole size is 1/2 inch (+/- 5/16) larger than fan blade size. Meets OSHA standards. UL listed 1 year limited warranty. Horsepower rating based upon maximum speed/load. Horsepower rating based upon maximum speed/load.