RK-W (with Temperature Controller)
These fans use a 3 speed motor with an integrated temperature controller. The target temperature is set by the adjustment dial. Once the temperature is detected above the target, it increases the speed of the fan to the 2nd speed. If the temperature increases further, the fan will step up to the highest (3rd) speed. The fan operates at the lowest speed when the temperature is below the set temperature, and doesn't turn off.