They advertised the worlds smallest oxygen concentrator with an extra battery pack with belt ( $599.000) included for just under $4000.00. I gave they my Visa and they sent the concentrator but not the battery pack. The concentrator alone will only allow me 1 1/2 hours ..not enough time to go to the store. I have been sending the emails, and leaving phone messages, since they no longer answer the phone, it isjust a recording. I have contacted the Manufacturer, Airsep Corporation and they said they do not sell to this company, however, they... read full review »