Patent ID: 8286635

Claim:
A mask system for use between a patient and a structure to deliver a breathable gas to the patient, the mask system comprising: a mask assembly including a frame and a cushion provided to the frame; and headgear removably attached to the mask assembly to maintain the mask assembly in a desired position on a patient's face, the headgear including a back headgear section providing a top strap and a pair of bottom straps; a pair of side straps, each of said side straps attached to a respective bottom strap; and an elastic strap attached to extend between the pair of side straps, wherein the elastic strap forms a fold, when the headgear is not worn, and is adapted to resiliently expand to conform to the patient's head, when the headgear is worn, wherein ends of the elastic strap are attached to respective ends of the bottom straps such that the elastic strap extends between and transversely to the bottom straps, and the bottom straps define a gap therebetween and the elastic strap includes a length that is greater than the gap when the headgear is not worn.