The present invention relates to a cushion for a patient interface that delivers breathable gas to a patient including a base wall structured to be connected to a frame, an underlying support cushion extending away from the base wall towards the patient's face in use, and a membrane provided to substantially cover at least a portion of the underlying cushion. The membrane is adapted to form a continuous seal on the patient's face. The underlying cushion has a springlike connection with the base wall. The underlying cushion and/or base wall define a spring constant that varies along a length of the seal.
