Power consumption
The maximum power consumed by the fan during operation. The higher the power consumption, the higher, usually, the greater the airflow rate created by the fan, and, accordingly, the higher the performance of the device. On the other hand, power usually directly affects the price, all other things being equal.
Number of speeds
The number of preset speeds at which the fan blades can rotate. The rotation speed is usually set by pressing the corresponding button (in addition, there is also a stepless adjustment, see the relevant paragraph). Most modern models with step adjustment have three preset speeds.
Maximum noise level
The maximum noise level produced by the fan when operating at the highest speed. For comparison: a noise of 30 dB corresponds to a distinguishable whisper at a distance of 5 m, 40 dB — to human speech, and 50 dB — to the sound background in an office room. The quieter the fan runs, the more comfortable it is to use.
