FIG. 1 is a front perspective view of a nasal mask showing our new design;

FIG. 2 is another perspective view thereof, taken from the rear;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right side elevational view thereof, the left side elevational view being a similar thereto;

FIG. 5 is a rear elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The portions drawn in broken lines are shown for illustrative purposes only and do not form part of the claimed design.