A foam-based interfacing structure method and apparatus

An interfacing structure for use with a mask including a frame. The interfacing structure comprises a securing component adapted to connect to a frame; and a cushioning component joined to the securing component and comprising a foam material that is configured to directly engage and form a seal with a patient's face. The securing component and the cushioning component together forming a cavity for receiving the patient's nose during use. An upper surface of the securing component is joined to a base surface of the cushioning component. The cushioning component includes: 1) an inner side (2090) adapted to face towards the cavity; 2) an outer side adapted to face away from the cavity; and 3) a base side adapted to face the frame or securing component, wherein the inner side and the outer side converge at an apex (2010) of the cushioning component that is configured to contact the patient's skin to form the seal therewith in use. In at least one first region of the interfacing structure, a plane of connection between the upper surface of the securing component and the base surface of the cushioning component is angled such that the plane of connection is not parallel to a tangent to the apex, and wherein, in at least one second region of the interfacing structure, an inner edge of the upper surface of the securing component is offset (apex 2010 and center line 2015 are spaced by distance 2020) from an inner edge of the base surface of the cushioning component.