I've been searching for so many months to find a good air purifiers, since i have 3 little kids, who are jumping around in the house all day long. I love Alen air purifiers. First of all, no compaines will say 'we will take care of your machine forever if you buy this products'. Everytime i smell something from the kitchen, i look at my Alen, to see what color it is, and I am very satisfied every time. As long as my budget allows me, I am going to buy a few more for my house. Thank you Alen.