An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. Oxygen masks may cover only the nose and mouth (oral nasal mask) or the entire face (full-face mask). They may be made of plastic, silicone, or rubber. In certain circumstances, oxygen may be delivered via a nasal cannula instead of a mask. Medical plastic oxygen masks are used primarily by medical care providers for oxygen therapy because they are disposable and so reduce cleaning costs and infection risks. http://www.midstarcylinders.com/