A mask apparatus for a respiratory treatment can permit delivery of breathable gas to a user. In one example, the mask may employ a frame and cushion to form a seal for both mouth and nose. The frame may be adapted for coupling with a respiratory treatment apparatus so as to permit communication of a pressurized gas from the respiratory treatment apparatus. The cushion, which may be foam, may have a substantially under the nose configuration or over the nose configuration. The mask may have a common plenum chamber for both nose and mouth. The cushion may further define a centrally open lip superior region. The cushion may be adapted to couple with the frame directly or to the frame in conjunction with a cushion support clip. Various features of the cushion may further promote sealing and comfort for the under the nose design.