Significant size filter for the 121 unit. I wish there was an indicator that would let me know when the filter is spent; I've enrolled for the filter subscription to ensure I don't overuse the filter (my last one was not changed for 2 years). Overall happy with the performance of the unit, which is running in my Loft most of the day, cleaning the air at that level of my home.
I would recommend this to a friend!
Written by a customer while visiting www.blueair.com