Simple and safe to use: The 5-liter medium-sized, neutral (natural flavor) Boost Oxygen canister delivers supplemental oxygen wherever you need it. Its filled with 99.5% pure supplemental oxygen—thats nearly five times the oxygen content of normal air, which contains about 21% oxygen. Supplemental oxygen is used by many people for a variety of reasons: from altitude acclimatization and athletics to older adults and anyone experiencing shortness of breath. Boost Oxygen provides all-natural respiratory support in a convenient, easy-to-use, and portable canister. Since 2007, Boost Oxygen has made portable supplemental oxygen available to everyone without a prescription. Breathe better, recover faster, and improve your performance with the 5-liter medium-sized, neutral (natural flavor) Boost Oxygen canister