So I never thought I needed this. I figured my air was pretty purified…but the reading says different. This was easy to set up and easy to use. I plugged it in and found my air was 73% purified! Horrified I ran that sucker for 5 hours and by the first 20 minutes the air was purified up to 90ish%! I was shocked! I have always trusted the shark brand but now I trust it even more!