a generally triangularly shaped frame of resilient material, the frame including an outer surface, an inner surface having an inwardly oriented rim extending along at least a portion of a perimeter of the frame and a notch adapted to receive the bridge of the wearer's nose; and

a generally triangularly shaped membrane of resilient material, the membrane including an aperture adapted to receive the wearer's nose, an outer surface including a seal forming portion adapted to deform and form a seal over a portion of the wearer's face when the mask is in use, an inner surface opposing the rim of the frame, an edge defining the perimeter of the aperture, and a notch in a region of the membrane adapted to receive the bridge of the wearer's nose, wherein

the membrane is more flexible than the frame;

the aperture of the frame is larger than the aperture of the membrane; and

the edge of the membrane, in use, is spaced a distance from the rim in at least the region of the membrane adapted to receive the bridge of the wearer's nose.