Okay, they are built solid. My Current Air Filters are 10 years old, and starting to fail (different brand). These come in looking very sleek/professional. Have a GOOD fan on them, so the air moves... Very well engineered. I recommend using a coupon code like CIRSLAB10 for 10% off. The value for the money gets a small ding, because they are on the expensive side.
My only other complaint is that the green ON light (LED) is too bright in a bedroom. Working on getting that addressed through the phone app...