OxyHealth chambers are a Class II medical device.  As indicated in the FDA 510(K) clearance, these chambers—both the portable mild and steel types—are prescription devices. 
The mild portable chambers are cleared for the treatment of oxygen deficiency due to High Altitude Sickness (also known as AMS) and its associated mild symptoms.
The steel chamber is cleared for the treatment of 13 recognized indications, which are:
1.  Air or Gas Embolism
2.  Carbon Monoxide Poisoning
Carbon Monoxide Poisoning Complicated by Cyanide Poisoning
3.  Clostridal Myositis and Myonecrosis (Gas Gangrene)
4.  Crush Injury, Compartment Syndrome, and other Acute Traumatic Ischemias
5.  Decompression Sickness  
6.  Enhancement of Healing in Selected Problem Wounds  
7.  Exceptional Blood Loss (Anemia)
8.  Intracranial Abscess
9.  Necrotizing Soft Tissue Infections
10. Osteomyelitis (Refractory)
11. Delayed Radiation Injury (Soft Tissue and Bony Necrosis)
12. Skin Grafts & Flaps (Compromised)
13. Thermal Burns

FDA regulations require that the chambers be sold to or on the order of a state licensed practitioner.