Flask cap

FIG. 1 is an upper, front, and left side perspective view of a flask cap showing our new design;

FIG. 2 is a lower, rear, and right side perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof.

Elements of the flask cap depicted using broken lines are intended to illustrate the environment of the claimed design and form no part of the claimed design.