WindShift Modular Fans feature clamshell knuckles that clamp each blade to a 0.25-in. steel center disk. Blade configuration and pitch angle, center disk diameter, and rotation are customer specified. Equally spaced blade configurations include 6, 7, 8, 9, 11, or 13 blades. Staggered blade configurations, which help reduce noise, are also available. Additional features include 3.08 to 6.32-in. pitch widths; 30 to 48-in. fan diameters; 1 to 5-in. standard pilots; and 18,000fpm maximum tip speed. The fans are available with clockwise or counterclockwise rotation. Horton Inc., 2565 Walnut St., Roseville, MN 55113, (888) 813-9926, www.hortonww.com/windshift