A universally fitting headgear that is readily adjustable to a variety of different sized patients and that couples a patient interface device to an airway of the patient. The headgear includes a headpiece that fits on the user's heal in a cap-like fashion. The circumference of the headpiece is adjustable...http://www.google.es/patents/US6805117?utm_source=gb-gplus-sharePatente US6805117 - Universal fitting headgear
