The Oxygen Concentrator easily transfers from one room to another. The small size of this concentrator makes it less obtrusive in the home and produces an oxygen output of 5 liters per minute (LPM). The 4L Home Oxygen Concentrator is feature-rich and comes at a low price, making it our best selling home oxygen machine. In fact, the 4L Oxygen Concentrator ranked early in a Comparison of Top Home Oxygen Concentrators. This oxygen concentrator is ideal for patients who lead an active lifestyle.