Satisfied. Seems a good product for a reasonable price, and it seems to last a long time.

Excellent product. Air is much cleaner. Lasts quite a long time

I'm in my second purchase of this filter set and yes it fits my 5510 perfectly! So thankful I found this listing. My bedroom has lost the stale musty smell and I never want to go back.

I bought the 5510 about two months ago. I keep it in my bedroom, and run it all night long while I sleep. Before I bought the machine, I would wake up every morning with plugged up sinuses and coughing up mucus. After having my WINIX 5510 for two months, all of that is gone. I get the best sleep of my life, and I wake up with clear sinuses and no cough.

Love this air filter. Cannot find a replacement filter. I've bought 3 now, and they claim to work with 5520 but they are 3x too big.