We recently purchased our 3rd Fit50. We have a 2400 sq ft home and we wanted to increase the coverage. We purchased 2 Fit50 units a little over a year ago. Living in Arizona, dust can be a problem but not with the Fit50. It is amazing how little dust we pick up in the vacuum. We also don't have to change the AC filters near as often. Completely satisfied and totally recommend Alen air purifiers.