I originally contacted AirPurifierSandCleaners.com about a particular expensive air cleaner. I got the information I requested, but also an invitation to get personalized (and free) advice. The advice was great! In the end I bought a less expensive machine (less expensive to buy, and less expensive to run) that really suits my needs (the AirDog A5 with FD filter that does not require replacement). AND I paid less than the Amazon price (much less since the FD filter came with the unit). Great advice, great price, super-responsive communication and solid shipping with tracking. I am a happy customer. : )