1.The patented design provides excellent performance without a cone. 2.Thick and corrosion resistance SMC housing with limited lifetime warranty . 3.Rust-free,corrosion-free,smc housing with onterior glossy for high output performance and low maintenance. 4.Every feature of cone fan line is designed to maximize performance and durability 6 blanced SMC paddle blades 5.Direct drive fan requiring no belts,no bearings to grease with high efficiency with no drive loss. 6.Totally enclosed,maintenance free ,high efficiency direct drive motors 7.Uniques shutter design lower resistance with preventing back drafts 8.Unique motor mount design allows you to quickly and easily remove all interior fan conmponts from inside of the building 9.Self draining ,sloped housing is quick and easy to clean reducing maintenance costs 10.Pvc coated outside guard