The central plastic part that holds the motor is not sturdy, resulting in quite a bit of vibration and a slight hum.
Especially if it is not screwed onto a flat surface, the noise is very noticeable due to the vibration.
The solution is to tighten it with the outer cover using a cable tie.
Otherwise, it blows a satisfactory amount of air outside the house.

very good and pulls the air quickly, replaced the same older one, not because it broke but because after many years the plastic around it turned yellow