Hyper Fan Digital Mixed Flow Fan - 6 Inch | 315 CFM | Energy Efficient Technology, Quiet Operation, Lightweight, Includes the Hyper Fan Speed Controller - ETL Listed Best in its class  delivering the highest CFM's per watt of any fan in the industry Hyper Fan's develop higher static pressures and higher airflows than any other mixed flow fans in the market. Volume (cf): 0.3281 They are the answer to a unified environmental solution for your garden Allows the motor to be energized 12 times per revolutuion. Delivering power to the fan blades smooth, ultra efficient, and vibration free. Multi-Phase EC Motors uses up <span class="a-text-bold"><span class="a-text-italic">HALF</span></span> the power and produce <span class="a-text-bold"><span class="a-text-italic">HALF</span></span> the heat of traditional EC or DC motors. This results in reduced energy costs along with less wear, increased reliability, and a longer expected lifespan than any other fan in its class. Programmed to slowly feed the power into the motor resulting in less wear and a longer lifespan. Included speed controller allows you to adjust fan speed from 35% - 100%. * The fan will automatically operate at full power without supplied speed controller This technology is the foundation for reduced noise, efficient operation, higher airflow, and the highest static pressure performance. Constructed the fan housings from lightweight aluminum. Use large, sealed self lubricating ball bearings (Opposed to less reliable needle roller bearings).