Its is the most recognized brand but priced at over 15 K I just dont see how people can actually pay for more then one unit which is recommended if you have more than one bedroom.
We have a house with multiple bedrooms and one machine wont cut it because you really cant assume that the particles in the air will make it from your babies bedroom all the way into the living room where the air purifier sits. This being said we felt it was more affordable and effective to set the Alen air purifiers in each room.