Mask Assembly

FIG. 1 is a front perspective view of a mask assembly showing our new design; FIG. 2 is a front view thereof; FIG. 3 is a rear view thereof; FIG. 4 is a right side view thereof; FIG. 5 is a left side view thereof; FIG. 6 is a top view thereof; and, FIG. 7 is a bottom view thereof. The even length broken lines in the drawings are for the purpose of illustrating portions of the mask assembly components that form no part of the claimed design.