Portable oxygen concentrator is a device that provides oxygen therapy to a patient while giving them more freedom to move about.  They perform the same functions as a home oxygen concentrator, yet are smaller in size and are very mobile.  Also, they have various options for energy sources, such as, plug in adapters for cars and long lasting rechargeable batteries.  The patients can also travel easily since they are small enough to fit in a car; a oxygen carrier, such as a backpack; and most of the major concentrators are now approved by the FAA for fllight travel.