Vacuum flask

[0001]FIG. 1 is a perspective view of a vacuum flask showing my new design;

[0002]FIG. 2 is another perspective view thereof;

[0003]FIG. 3 is a front elevational view thereof;

[0004]FIG. 4 is a rear elevational view thereof;

[0005]FIG. 5 is a left side view thereof;

[0006]FIG. 6 is a right side view thereof;

[0007]FIG. 7 is a top plan view thereof; and,

[0008]FIG. 8 is bottom plan view thereof.

[0009]The broken lines illustrate portions of the vacuum flask which form no part of the claimed design.