A mask system for use between a patient and a device to deliver a breathable gas to the patient includes a mouth cushion, a pair of nasal prongs, an elbow, and a headgear assembly. The mouth cushion is structured to sealingly engage around an exterior of a patient's mouth in use, and the pair of nasal...http://www.google.com/patents/US20060283461?utm_source=gb-gplus-sharePatent US20060283461 - Mask system
