Breathing mask and a sealing lip device for a breathing mask

An elastomeric cushion for a breathing mask configured for sealed delivery of a flow of breathable gas at a positive pressure with respect to ambient air pressure to an entrance of a patient's airways including at least an entrance of the patient's nares, the elastomeric cushion having zones of differing load-bearing capability, wherein a first zone includes a zenith of the cushion, a second zone is positioned opposite the first zone and a pair of intermediate zones extend between the first and second zones, the elastomeric cushion comprising:

• a peripherally extending shell engaging portion configured to secure the elastomeric cushion to a shell of the breathing mask;
• a peripheral wall extending from the shell engaging portion and defining a plenum chamber, a portion of the peripheral wall in the first zone being more collapsible that portions of the peripheral wall in the second zone and the intermediate zones so that the cushion is pivotable around an axis that is between the first zone and the second zone and extends through the pair of intermediate zones;
• and
• an engagement surface defining an opening to the breathing chamber and being configured to engage the patient's face, the peripheral wall extending from the shell engaging portion to the engagement surface,
• wherein portions of the engagement surface in the first zone and the second zone have a relatively thin elastomeric wall compared to elastomeric walls of the portions of the elastomeric surface in the pair of intermediate zones.