Prior to the introduction of the Aerox system, wise pilots reserved the use of oxygen for situations where it was legally necessary, i.e. above 12,500 ft. This was often a practical decision based upon factors like: Short duration of supply, uncomfortable masks, difficult & costly refills, heavy weight and large bulk. Aerox systems address these objections with advanced designs and materials that help make oxygen use easier, more comfortable, and less expensive than ever before. Add to your flying comfort by using oxygen at altitudes as low as 5000 feet.