FIG. 1 is a perspective illustration, from the bottom and right side, of a cushion for a mask according to our design in which the cushion includes an inner rim and an outer membrane spaced apart from an inner rim;

FIG. 2 is a reverse perspective illustration of the cushion shown in FIG. 1;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a left side view thereof, with the right side view being a mirror image thereof;

FIG. 6 is a rear view thereof; and,

FIG. 7 is a front view thereof.

Where included, broken lines showing environment or structure are for illustrative purposes only and form no part of the claimed design.