A patient interface comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmH 2 O above ambient air pressure, said plenum chamber including a plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for breathing by a patient, a seal-forming structure constructed and arranged to form a seal with a region of the patient's face surrounding an entrance to the patient's airways, said seal-forming structure having a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient's nares, the seal-forming structure constructed and arranged to maintain said therapeutic pressure in the plenum chamber throughout the patient's respiratory cycle in use; a positioning and stabilising structure to provide a force to hold the seal-forming structure in a therapeutically effective position on a head of a patient, the positioning and stabilising structure comprising: at least one gas delivery tube to deliver the flow of air to the entrance of the patient's airways via the seal-forming structure, the at least one gas delivery tube being constructed and arranged to contact, in use, at least a region of the patient's head superior to an otobasion superior of the patient's head; wherein the at least one gas delivery tube includes an inner textile layer and an outer textile layer, wherein the inner textile layer and the outer textile layer are joined along a first longitudinal edge at a first joint and along a second longitudinal edge at a second joint; wherein between the first joint and the second joint the outer textile layer is spaced from the inner textile layer; characterized in that the outer textile layer is thermoformed to have a predetermined shape and the inner textile layer is not thermoformed; and wherein the outer textile layer; supports its own weight between the first j oint and the second joint such that the outer textile layer remains spaced from the inner textile layer when not supported by pressurized air. a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmH 2 O above ambient air pressure, said plenum chamber including a plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for breathing by a patient, a seal-forming structure constructed and arranged to form a seal with a region of the patient's face surrounding an entrance to the patient's airways, said seal-forming structure having a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient's nares, the seal-forming structure constructed and arranged to maintain said therapeutic pressure in the plenum chamber throughout the patient's respiratory cycle in use; a positioning and stabilising structure to provide a force to hold the seal-forming structure in a therapeutically effective position on a head of a patient, the positioning and stabilising structure comprising: at least one gas delivery tube to deliver the flow of air to the entrance of the patient's airways via the seal-forming structure, the at least one gas delivery tube being constructed and arranged to contact, in use, at least a region of the patient's head superior to an otobasion superior of the patient's head; wherein the at least one gas delivery tube includes an inner textile layer and an outer textile layer, wherein the inner textile layer and the outer textile layer are joined along a first longitudinal edge at a first joint and along a second longitudinal edge at a second joint; wherein between the first joint and the second joint the outer textile layer is spaced from the inner textile layer; characterized in that the outer textile layer is thermoformed to have a predetermined shape and the inner textile layer is not thermoformed; and wherein the outer textile layer; supports its own weight between the first j oint and the second joint such that the outer textile layer remains spaced from the inner textile layer when not supported by pressurized air. at least one gas delivery tube to deliver the flow of air to the entrance of the patient's airways via the seal-forming structure, the at least one gas delivery tube being constructed and arranged to contact, in use, at least a region of the patient's head superior to an otobasion superior of the patient's head; wherein the at least one gas delivery tube includes an inner textile layer and an outer textile layer, wherein the inner textile layer and the outer textile layer are joined along a first longitudinal edge at a first joint and along a second longitudinal edge at a second joint; wherein between the first joint and the second joint the outer textile layer is spaced from the inner textile layer; characterized in that the outer textile layer is thermoformed to have a predetermined shape and the inner textile layer is not thermoformed; and wherein the outer textile layer; supports its own weight between the first j oint and the second joint such that the outer textile layer remains spaced from the inner textile layer when not supported by pressurized air.