Simple and safe to use, the Medium Size Natural 5 Liter Canister from Boost Oxygen provides supplemental oxygen wherever you need it. It is 95% pure supplemental oxygen which is nearly 5 times the amount of normal air, which is around 21% oxygen. Supplemental oxygen is used by so many people for so many different reasons. From altitude acclimation to athletes to older adults and to 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 performance with the Medium Size Natural 5 Liter Canister from Boost Oxygen.