These fans are specifically designed to bridge the transition between centrifugal and axial by combining the high flow of axial designs with the higher pressure, non-over loading characteristics of backward curved impellers. Galvanized steel hous ing as above with baked powder coat finish. External motor with built-in thermal over load protection and automatic reset. Permanently sealed ball bearings. External wiring box for ease of connection. 100% speed control-lable. Mixed flow impeller. Suitable for air stream temperatures up to 140 F. Excellent heat dissipation to ensure long motor life. Tested and approved by UL and CSA. 3 Yr Factory Warranty.