A container for storing oxygen under pressure is disclosed that includes a chamber adapted to be worn around a user's waist and adapted for supplying oxygen to the user; the chamber defining a volume to contain oxygen under pressure; wherein the chamber is defined by a central portion extending between opposite side portions; wherein each of the opposite side portions has a height greater than a maximum height of the central portion that further defines a void between the side portions and above the central portion; and wherein the chamber is further defined by an exterior surface of the chamber adjacent the user.