Alan air purifiers are simply the best out there.
Their lifetime guarantee makes it a smart choice .
I had a problem where my air purifier fit 50 stoped working I contacted Alan and they Replaced my air purifier with another air purifier of the exact same model 
The replacement works Great !

I also purchased a larger air purifier from Alin that does 1100 sq ft.
And it too is amazing .
I truly believe that Alan does as they say .Do the best they can to make the best air purifier around.