A small vessel intended to hermetically surround a patient's limb for the topical application of oxygen (O2) from an O2 gas supply at a pressure slightly greater than atmospheric (e.g., 1 to 2 atm) during hyperbaric oxygen therapy (HBOT). The device is typically a rigid or flexible plastic shell with valves and tubing for connection to an O2 source. It is typically used to treat skin ulcerations, decubitus ulcers, infected stumps, skin grafts, burns, and frostbite.