FIG. 1 is a top, front and left side isometric view of a drinking flask showing our new design;
FIG. 2 is a bottom, rear and left side isometric view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a front elevation view thereof;
FIG. 6 is a rear elevation view thereof;
FIG. 7 is a right side elevation view, the left side being a mirror image thereof;
FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 3; and,
FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 3.
The broken lines in the drawings depict portions of the drinking flask that form no part of the claimed design.