Effect exists, but there are cheaper alternatives

Since I myself am suffering from a dust allergy, I really wanted to have this filter for my radiator in the bedroom. These can be placed directly on the heater or installed below the grid. There they reduce the heated air through the rise of dust, which is otherwise continuously transported by the airflow through the room.
I really noticed an improvement in my symptoms and fall asleep at night even better (just the nose is not as often).
But these are really in this package only 3 of these filters available, is already really ridiculous for the price. My brother in law Heizungsbauer and showed me the hardware store a similar product at a much more attractive price and I have the other rooms now equipped with it.