US D597202 S1
The ornamental design for a respiratory mask, as shown.
FIG. 1 is a front perspective view of a respiratory mask according to our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof; and,
FIG. 6 is a right side view thereof with the left side view being a mirror image thereof.