Blueair Classic 500/600 Series Genuine DualProtection Filter; Classic 501, 503, 505, 510, 550E, 555EB, 580i, 601, 603, 650E, 605

Fit perfectly! No issues to date. Because of where we live, we only have to replace our filters every two years so these are worth the investment. I was surprised when I pulled out the old filters at all the dust they had accumulated. The air cleaner and filters work well.

Yes, they are pricey. Other, cheaper brands of replacement filters may claim to be compatible, but you will be compromising the performance of the unit and may even damage it. I'm not a shill for BlueAir, but we own 7 of their filters and they work great. It's important to understand BlueAIr units do *not* use HEPA filter media, but they *achieve* HEPA filter media performance using a unique combination of an ionization chamber where air is drawn into the unit (imparting a charge to particles in that air) and a filter media which builds up an opposite charge from the friction of air molecules passing through the media. The opposite charge attracts the charged particles in the air stream and binds the particles to the filter media, removing them from the air stream which then passes into the room. This means the unit *as a whole* removes just as many impurities as a HEPA filter, while providing a much higher clean air delivery rate (CADR) over a wider area than a HEPA filter, as HEPA media greatly restricts the airflow due to the high density of the media. Additionally, it is harder for the fan in the unit to push air through denser HEPA filter media, creating back pressure which causes excessive wear on the fan motor. All I can say is our BlueAir units are still going strong after over 20 years of continuous, daily use using authentic BlueAir replacement filters. We've also had some HEPA filter units which took longer to clean the air, only improved the air quality in a portion of a room, were much noisier and eventually became unusable after a few years due to fan motor bearing failure (which made them very noisy, even though they technically still functioned), or the lack of availability of replacement filters.

Blue air, classic, dual protection filters really work. I live in a dusty prairie community, where summertime pollen and fire and wildfire smoke are a daily issue. These filters are our final level of defense after HEPA filtering all of the incoming air to our house as it circulates the, six month change interval works even under these conditions. Of note: I received very professional and thorough assistance from Amazon when an issue issue. Issue a rose. with shipping. I especially appreciate the help because these filters are sometimes hard to get and the substitute generic types do not seem as effective, especially with smoke. Thanks

I've been using these filters for about 8 years. They are really good and normally more expensive elsewhere.

They do fit a little better than some of the knockoffs, but like some other reviewers noted, ironically, the filters start to smell. I'm in a studio apartment so the air can get stale quickly, and for a week or two the carbon layer did a great job making the place smell fresher. Unfortunately, activated carbon/charcoal doesn't sustain its odor absorbing capabilities very long, and now a weird kind of sour smell persists that's easy to mistake for old sweat or a gross mattress. I just spent the weekend deep cleaning my apartment including all my uphostlery to try and get rid of the mystery smell, only to realize it was actually coming from the one thing that was supposed to be helping and I didn't think to sniff in the first place. If my apartment were bigger, had better airflow, or if I were in a large house I might not notice it. I've had the unit for a decade+ and have never had smell issues with the normal knock-off filters w/o the carbon layer, serves me right for splurging I guess. On the upside my apartment's really clean now.