The 5 L offers medium oxygen flow and are the staple for home oxygen therapy, delivering adequate oxygen flow for over 90% of oxygen patients. Normal oxygen saturation of the hemoglobin (SpO2) is at 95 to 98%. Acceptable oxygen saturation is at 90%. When a patient is below 90%, doctors prescribe oxygen therapy. It is mainly used for critically ill patients, people who need to use a ventilator, and people who need long-term oxygen inhalation every day: copd, lung fiber, pneumonectomy, lung cancer, pneumoconiosis, silicosis and other people. The 5 L is very effective and made for medical uses.