A RESPIRATORY USER INTERFACE

There is provided a user interface (201) comprising an under-nose seal full face mask which comprises:a. a mask body (203);b. a mask cushion (205) attached to the mask body and configured to comprise a mouth seal portion (205A) forming a seal around a user's mouth and a nose seal portion (205B) forming a seal around the underside of the user's nose in use;wherein the mask body and mask cushion together define an interior chamber of the user interface;c. a breathing gas delivery inlet (209) provided in the mask body and configured to receive a breathing gas flow from a gas source;d. a pair of non-sealing nasal prongs (223); ande. a breathing gas flow director configured to split the breathing gas flow into two flow paths, such that a portion of the breathing gas flow is delivered along a first flow path (F2) from the inlet into the interior chamber to pressurise the interior chamber, and such that a portion of the breathing gas flow is delivered along a second flow path (F3) from the inlet through the nasal prongs; wherein the nasal prongs are configured to be connected to the breathing gas flow director and are shaped and dimensioned to be received in a user's nares in use.