Oh I'm so glad I was asked to do a review. I love Blue Air purifiers I first bought in 2022 one month before my husband came down with covid for the first time. I had just bought 411 Auto purifiers for every room. He's had covid two or three more times since then, I have never had it. I think these purifiers helped. I don't have anything scientific to prove it though I purchased mini max last year for kitchen, bathrooms, laundry room, pantry. I've bought extra pre-filters a couple of times, everything was fine. This last time, May or June 2025, the one that arrived that is supposed to fit my mininmax, is too long, too tall, does not taper, and looks sloppy. I showed it to them, uploaded the photos and they're just trying to convince me I don't know what I'm talking about. In fact one chat person said well I'm sorry it doesn't fit your 411 and I said I am talking about the minimax which is not the 411. All the pre filters I have for the 411s are fine. I'm not sure where he thought I was talking about that one but I repeatedly uploaded the photo of the saggy stretched out when on the mini Max which looks awful. Was a waste of money I don't know what has happened because Blue Air was reliable and dependable and I'm really disappointed. I have a pre-filter that doesn't fit and they should ship me another one.