Returns are accepted from US Oxygen Sales within 7 days of receipt for an exchange or a refund of the purchase price excluding our shipping and handling costs. Most items are subject to a 10-15% restocking fee. During those 7 days feel free to use the unit and make sure it is to your satisfaction, for fewer than 20 hours over the manufacturer’s test hours. In the event that the unit has a smoke odor, no return will be accepted. No unit will be accepted without a return merchandise authorization (RMA). To obtain an RMA, please call us at 888.632.2235 and we will help process the return. There are no returns for home oxygen concentrators. US Oxygen Sales is not responsible for any return damage from the freight forwarder upon receipt. Please obtain tracking from the freight forwarder when shipping back to have visibility of the return. Please make sure the unit is in its original packaging and is complete to obtain refund.