Abstract: A mask system for treating sleep disordered breathing. The mask system includes headgear and a combination shell and cushion. A plurality of ribs provide rigidity to the combination shell and cushion and are formed integrally with the combination shell and cushion. The mask system also includes a frame shaped and adapted to be removably mounted on the combination shell and cushion. The frame has a plurality of headgear anchor points. A retaining ring is positioned adjacent the front aperture. In addition, a rotatable elbow has a proximal end, a distal end and circumferentially equi-spaced diametrically opposed tongues with undercuts. The proximal end is adapted to pass through the retaining ring. The distal end is adapted to engage an air delivery tube, and the undercuts are adapted to engage the retaining ring. Also, a seal allows rotation of the rotatable elbow relative to the combination shell and cushion.

Abstract: A mask system for treating sleep disordered breathing, comprising headgear, a shell/cushion including a channel adjacent a front aperture, a frame, an elbow including at least one undercut on a proximal end, a retaining ring including a rear flange adapted to be retainably insertable in the channel of the shell/cushion, and a front flange adapted to retainably engage with the at least one undercut of the elbow.

Abstract: A mask system for treating sleep disordered breathing, comprising headgear, a shell/cushion including a channel adjacent a front aperture, a frame, an elbow including at least one undercut on a proximal end, a retaining ring including a rear flange adapted to be retainably insertable in the channel of the shell/cushion, and a front flange adapted to retainably engage with the at least one undercut of the elbow.

Abstract: A mask system for treating sleep disordered breathing, comprising headgear, a shell/cushion including a channel adjacent a front aperture, a frame, an elbow including at least one undercut on a proximal end, a retaining ring including a rear flange adapted to be retainably insertable in the channel of the shell/cushion, and a front flange adapted to retainably engage with the at least one undercut of the elbow.

Abstract: A mask system for treating sleep disordered breathing, comprising headgear, a shell/cushion including a channel adjacent a front aperture, a frame, an elbow including at least one undercut on a proximal end, a retaining ring including a rear flange adapted to be retainably insertable in the channel of the shell/cushion, and a front flange adapted to retainably engage with the at least one undercut of the elbow.

Abstract: A mask system for treating sleep disordered breathing, comprising headgear, a shell/cushion including a channel adjacent a front aperture, a frame, an elbow including at least one undercut on a proximal end, a retaining ring including a rear flange adapted to be retainably insertable in the channel of the shell/cushion, and a front flange adapted to retainably engage with the at least one undercut of the elbow.