Description:? This WhisperGreenT model features built-in intelligence called SmartFlowT Optimum CFM Technology. This unique "electronic-brain" lets the fan do what was once thought to be impossible, perform at a constant CFM regardless of elbows and other factors that might hinder performance. Basically, when a WhisperGreenT fan faces static pressure, its speed is automatically increased to ensure that the desired CFM is actually achieved. This allows the fan to perform as rated and makes for easier installation because the installer no longer has to worry as much about compromising the fan"s performance. Uses ultra energy-efficient DC motor. UPC Code: 885170012196