Mask

FIG. 1 is a top front isometric view of a mask showing the claimed design;

FIG. 2 is a top rear elevation view thereof;

FIG. 3 is a bottom rear isometric view thereof;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is a right side elevation view thereof;

FIG. 7 is a left side elevation view thereof;

FIG. 8 is a top plan view thereof; and,

FIG. 9 is a bottom plan view thereof.

The broken lines in the figures show portions of the mask that form no part of the claimed design.