Patent ID: 7874291

Claim:
A respiratory mask assembly for delivering breathable gas to a patient, comprising: a frame having a front surface and a rear surface, opposite the front surface, and adapted in use to face the patient, the frame defining an inner wall and an outer wall extending from the rear surface, the inner and outer walls being rigid and spaced to define a channel therebetween, the channel including a bottom surface defined by the frame; and a cushion being removably attachable to the frame such that the cushion and frame are repeatably engagable with and disengagable from one another, the cushion including a side wall to be inserted into the channel of the frame, the side wall having a first interlocking surface that engages a second interlocking surface provided in the channel when the cushion and frame are engaged with one another, wherein the first and second interlocking surfaces interlock with one another to removably attach the cushion to the frame, and the first and second interlocking surfaces are configured such that an engagement force for engagement of the cushion to the frame is less than a disengagement force for disengagement of the cushion from the frame.