I got a "new" pro neb ultra off the internet from allergybegone.com
It was working great for three weeks or so. All of sudden for no explantion, it gets about 10x louder. It still works but the noise is out of control. What the heck happened? I'm thinking of trying to send it back and get the new version. In my haste I ordered the older version, but should have gotten the upgrade. I could have expected this after a year or so, but only three weeks in. That bothers me.