Elastic headgear

A patient interface system for providing pressurized breathable gas to a patient's airways to treat sleep disordered breathing, the patient interface system comprising:

• a mask comprising:
• a cushion;
• and
• a mask frame;
• headgear connected to the mask frame to retain the mask on the patient's face during treatment, the headgear comprising:
• a first rigidizer and a second rigidizer, the first rigidizer and the second rigidizer each having a curvature that substantially conforms to a corresponding portion of the patient's face in use;
• and
• a strap having a first free end, a second free end, a back portion, a first side portion, and a second side portion, the first side portion and the second side portion being joined to the back portion opposite one another, the strap being constructed from an elastic material,
• wherein the first free end engages the first rigidizer to connect the first side portion to the first rigidizer such that the first rigidizer substantially imparts its curvature upon the first side portion of the strap and the second free end engages the second rigidizer to connect the second side portion to the second rigidizer such that the second rigidizer substantially imparts its curvature upon the second side portion of the strap, and
• wherein the first side portion and the second side portion are stretchable relative to the first rigidizer and the second rigidizer, respectively.