HIGH SPEED EC MOTOR

We have been selling these fans for 3 years and never had we had one come back. 

200mm

This fan incorporates a digital, EC (Electronically Com-mutated) DC motor that provides superior performance and efficiency beyond what is possible with traditional AC motors. The High Speed type uses a 3-phase design that pushes the boundaries of performance for a fan of this class.

3-MODE ENVIRONMENTAL CONTROLLER can be added for $60.00

A digital 3-mode Environmental Controller is included to provide the user with total control. One mode allows for manual control of the fan’s speed, while two thermostat-controller modes either turn off the fan, or reduce its speed when the temperature of the room falls below set temperature.

The addition of an environmental controller (sold separately) will allow these fans to be speed and temperature controlled:
https://www.homegrownkiwi.com/products/mountain-air-mountain-air-environmental-daisy-chain-controller/