Thousands of people on oxygen therapy have benefited from the new designs of portable oxygen systems. An active life style and being able to move about freely is especially important to patients on oxygen therapy. For most people it is necessary but not a limitation but for oxygen therapy patients it is a factor they have to take into account all the time.The type of oxygen delivery system you will have has to take into account: * Your oxygen therapy – how often, is it continuous? *The amount of oxygen you receive. * The type of activities you have.It is a good idea that both you and your doctor define together the type of oxygen system you will use – his expertise and your own knowledge of your activity levels. Once you begin to receive oxygen through a particular oxygen delivery system, or as is generally the case, combination of systems, you adjust and get used to that system (including make and model) which is good news. The bad news is that once you are used to it, it is difficult to change. So it is best to get it right and to do this, both you and your doctor have to work together.There are only three different types of oxygen delivery systems, two of these store it. (The three systems have both home based and portable alternatives).1. Portable Oxygen Concentrators – An oxygen concentrator is a machine, electrically powered, that extracts oxygen from ambient air, concentrates it at 100% and then delivers it to the patient either though a cannula or an oxygen mask (much like the other systems). The portable ones are smaller and lighter. As they are electrically powered this is by plugging into the wall socket (or car lighter adapter), as well as with rechargeable batteries. This versatility is making them very popular with the additional advantage that most brands are looking to increase the battery duration. 2. Portable Oxygen Cylinders – Perhaps the oldest type of oxygen delivery system. Pure oxygen is compressed and stored in aluminum cylinders. These cylinders come in various sizes (from 4 to 8.5 lbs in weight). Again the stored oxygen will last depending on the amount of oxygen that is delivered, but a general rule of thumb is that they last for shorter periods of time compared to the other systems. Note: Oxygen cylinders are refillable.3. Portable Liquid Oxygen Tanks – Oxygen has the physical property of turning liquid at lower temperatures. Liquid oxygen tanks keep a reservoir of liquid oxygen (which by the way means a much greater amount of oxygen is stored than if kept in its gaseous state), which is then delivered at the appropriate setting as a gas (obviously the tank has a gas small gas storage part). There small units available that can deliver oxygen for many hours.