Think Crucial Replacement for Deluxe Blueair 400 Air Purifier Filter Fits ALL 400 Series Air Purifiers HEALTHIER LIFESTYLE! No one wants to breathe in dirty air and if you don't clean your air filter that will be exactly what you'll be doing! Replacing your filter will help clean your air and allow for a healthier lifestyle! This filter fits ALL Blueair 400 Series Air Purifiers. EASY TO INSTALL so you can get back to breathing clean air as soon as possible! Simply remove your old filter and put this brand new one in it's place! SAVE MONEY by using a new air filter! When your Blueair Air Purifier has a clogged or dirty air filter it can cause it to work harder which will end up hurting your electric bill! GUARANTEED SATISFACTION because of a 30 day full money bank guarantee and a trusted Think Crucial warranty. We are so confident in our products that we have no problem giving you every penny back if you're unhappy with your purchase. You won't see promises like that from big box brands!