The two Alen purifiers we ordered and installed have made a great difference in our home. The air is so clean and I suffer from allergies. I breath much better and the clean air has improved my allergies to the point I can sleep all night. I have been able to cut back on inhalers and other medications. My wife says I no longer snore at night. The machines have really made a difference in our home. I would give the machines an A+.