We now have six Alen units, the first of which was the A375UV purchased about eight years ago. This one has a modern look and feel to it and operates a lot like the full-sized BreathSmart we purchased a few years ago when they first came out. It's quite quiet; almost too quiet. We were actually hoping it would create a little "white noise" in an office setting. We barely hear it unless we unless we set it to "turbo".