Designed to ventilate stores, greenhouses, offices, factories, shops, farm buildings, etc. Efficient, easy-to install exhaust fan with automatic shutters. Steel intake guard complies with United States OSHA Federal 1/2 in max opening requirement. Wire guard has charcoal gray metallic polyester finish to resist corrosion. Blades are manufactured from galvanized steel ant the motor is totally enclosed. Shutter frames with prepunched mounting holes allow for easy installation. This is a ready to install unit for wall mount only.