Patent ID: 7318439

Claim:
A respiratory mask assembly for use in the delivery of non-invasive positive airway pressure to a user, comprising: a substantially rigid shell including a plurality of receiving portions; a cushion detachably connected to the shell, said cushion having a retaining channel, a retaining lip adjacent the retaining channel, and a sealing portion extending from the cushion to engage a portion of the shell to provide a continuous airtight seal between the cushion and the shell; and a retaining ring to secure the cushion to the shell, the retaining ring being received within the retaining channel of the cushion prior to engagement with the shell to form a cushion and retaining ring sub-assembly, said retaining ring having a plurality of projecting engagement members configured to engage a respective one of the receiving portions of the shell when the cushion and retaining ring sub-assembly is assembled with the shell along a push-on direction, wherein at least a portion of the retaining channel extends in a radial direction of the cushion relative to the push-on direction.