Flask

FIG. 1 is a top perspective view of a flask showing our new design according to a first embodiment; FIG. 2 is a bottom perspective view thereof; FIG. 3 is a front elevation view thereof, wherein a rear elevation view thereof is a mirror image of the front elevation view; FIG. 4 is a left-side elevation view thereof, wherein a right-side elevation view thereof is a mirror image of the left-side elevation view; FIG. 5 is a top plan view thereof; FIG. 6 is a bottom plan view thereof; FIG. 7 is a top perspective view of the flask according to a second embodiment; FIG. 8 is a bottom perspective view thereof; FIG. 9 is a front elevation view thereof, wherein a rear elevation view thereof is a mirror image of the front elevation view; FIG. 10 is a left-side elevation view thereof, wherein a right-side elevation view thereof is a mirror image of the left-side elevation view; FIG. 11 is a top plan view thereof; and, FIG. 12 is a bottom plan view thereof. Broken lines in the figures illustrate portions of the flask that form no part of the claimed design.