Crowley Company, Inc.'s (Burton, OH) multi-wind X Series fans feature a twisted airfloil blade profile that is designed to attain high air volume, low power consumption, and make little noise, according to the manufacturer. The fans are available in diameters from 36 to 78 in., four corrosion-resistant blade materials, configurations from 3 to 10 blades, and pitch angles from 25 to 50 degrees.