The filter on the left is what I pulled out of my Levoit Pet air purifier that runs in my bedroom every single night. The one on the right is the fresh replacement. I am horrified. Studies show indoor air can be up to 5x more polluted than outdoor air and seeing this makes me believe it. I have three of these, one on every floor of my house. If you have pets this is non-negotiable. I have three cats and recently had someone over who is allergic to cats and they had ZERO allergy symptoms. I also keep one right next to the litter box and I literally cannot smell it. This brand just works. Highly recommend. I personally own both exact models tagged. The square one has a washable pre filter that can make your filter last longer. airpurifier detox healthyhome catmom homemustahaves amazonfinds amazonfavorites healthandwellness nontoxichome nontoxicliving homeessentials LTKHome LTKBaby LTKmomlife