Blueair PRO M Replacement Particle Filter

I keep this air purifier on medium, and it is pretty quiet. Low is basically silent, and medium has very little noise. High works well but probably is not ideal if you are sleeping in a bedroom with it. I didn't realize how well it worked until recently, when I forgot to change the filter. I noticed the air in my bedroom was not as good, and my allergies were acting up. Then I checked when I last changed the filter (something was covering up the red filter change light, so I didn't see the alert), and I realized it has been over 7 months. When I changed the filter, it was COVERED in dust...a thick layer. I've now set the reminder to change my filter so this issue doesn't come up ever again! Definitely an excellent product (as are all the Blueair, though this one might be better than the Sens and 200/300 series)