A patient interface (3000, 6000, 7000, 8000, 9000) comprising: a plenum chamber (3200, 9200) 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 (3100, 9100) 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 (3300, 7300, 8300, 9300) 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 (3300, 7300, 8300, 9300) 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 (3100, 9100), 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; characterized in that the at least one gas delivery tube includes: an elongate, tubular textile portion having an exterior surface and an interior surface; the elongate, tubular textile portion being constructed from an outer textile portion and an inner textile portion that are connected by joints; and an impermeable layer comprising a single, homogeneous piece of material joined to the interior surface of the elongate, tubular textile portion by blow molding such that the impermeable layer is circumferentially continuous. a plenum chamber (3200, 9200) 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 (3100, 9100) 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 (3300, 7300, 8300, 9300) 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 (3300, 7300, 8300, 9300) 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 (3100, 9100), 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; characterized in that the at least one gas delivery tube includes: an elongate, tubular textile portion having an exterior surface and an interior surface; the elongate, tubular textile portion being constructed from an outer textile portion and an inner textile portion that are connected by joints; and an impermeable layer comprising a single, homogeneous piece of material joined to the interior surface of the elongate, tubular textile portion by blow molding such that the impermeable layer is circumferentially continuous. 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 (3100, 9100), 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; characterized in that the at least one gas delivery tube includes: an elongate, tubular textile portion having an exterior surface and an interior surface; the elongate, tubular textile portion being constructed from an outer textile portion and an inner textile portion that are connected by joints; and an impermeable layer comprising a single, homogeneous piece of material joined to the interior surface of the elongate, tubular textile portion by blow molding such that the impermeable layer is circumferentially continuous. an elongate, tubular textile portion having an exterior surface and an interior surface; the elongate, tubular textile portion being constructed from an outer textile portion and an inner textile portion that are connected by joints; and an impermeable layer comprising a single, homogeneous piece of material joined to the interior surface of the elongate, tubular textile portion by blow molding such that the impermeable layer is circumferentially continuous.