I ordered 2 sets for my 2 Winix Plasmawave 5500 Models and they fit perfectly. The main filter fits super snugly and the carbon pre-filter also sits perfectly in place for a nice fit.
I am very happy that I was able to find the true genuine made by Winix filters here on Great Offer Stock, instead of buying the "made for" generics available elsewhere, which also didn't offer the genuine version, because these air filtration machines are so top notch in performance I didn't want to compromise one bit when buying replacements. (I have used the generic types for my old Hunter machines but this machine delivers such results I just thought - worth the money! and it really is!)
For those wondering - Yes the box states made by Winix on it to assure you it's the genuine article. It's not 99% or 99.7% that generics offer. The true Winix replacements are the highest at 99.97% removal rate of all airborne allergies including pollen, mold spores, dust, pet dander, microbes and smoke (0.3 microns in size or larger).
Also on the box if you wonder if this will fit your model they offer a phone number to call: 814-703-8458. I knew if these fit the 5300 model they would also fit my 5500 and they do.
The manufacturer states the main white filter lasts up to a year and that the carbon pre-filter should last 3 months (so they provide 4 for the year). I personally find I like to vacuum off the hairy build up on the pre-filter that comes from dust, and hair from me and my cat, every week or so. I've also washed the pre-filter in soapy water, let dry and reused as well, but they should be replaced with new since washing will remove the carbon which removes odors.
In my NYC apt, the main filter needed replacement after 9 or 10 months I believe. I did try washing it as the original one form the machine stated it was washable but it really didn't get truly clean so I used it for 2 more months before buying these replacements.
As soon as I cleaned out my machine and put my new filters in, I noticed how pure the air was coming out when turned back on. Made me realize not to leave it too long. Highly recommend buying the manufacturer made filters!
I hope Great Offer Stock continues to sell them long term, because I will be back for more when needed!
PS remember to reset your filter button under the machine's front cover to get the air filter light to turn off and reset, once it goes on to warn you it is time to replace your filter. Thought I would mention that because I notice people don't read the manual that comes with the machine on operation, so I see so many reviewers complain of lights staying on etc. which all the answers will be in the manual! : )
In this case of changing the filter, its a button you press and hold until the light goes off. Hope this helps).