The invention relates to a cushion for use as part of an apparatus for supplying a flow of respiratory gases to a user. A toothed profile is formed on the face side of the cushion. The toothed profile comprises at least one tooth aligned inwards towards a centre of the cushion. A side of the at least one tooth is coterminous with the face side of the cushion and an opposite side of the at least one tooth is conterminous with an inside surface of a perimeter wall of the cushion, so that an apex of the tooth is formed where the inside surface of the perimeter wall meets the face side of the cushion.
