There's a good reason why oxygen concentrators are gaining more and more popularity over the use of oxygen tanks. You no longer have to order oxygen refills, which ends up saving you money in the long run. Oxygen concentrators are called so, because they take in the air around them and concentrate it into a much higher purity of oxygen.
Another reason someone might choose an oxygen concentrator over tanks, is the fact that you can use them during a flight. There are many portable oxygen concentrators that are pre-approved by the Federal Aviation Administration. Even though you need to recharge your portable concentrator's battery, they are still more convenient to most people than tanks.
If you need oxygen therapy, and you want to use an oxygen concentrator, the first thing you'll need to do is talk to your doctor. If he or she thinks one would be right for you, they might help you choose one. Either way, you will need your oxygen dosage prescription to order an oxygen concentrator from a reputable, accredited seller.