The ornamental design for a double pocket, as shown and described.
FIG. 1 is a front view of a double pocket, showing our new design;
FIG. 2 is a rear view thereof;
FIG. 3 is a left side view thereof with a right side view being a mirror image;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is an exploded rear view thereof; and,
FIG. 7 is an exploded left side view thereof with an exploded right side view being a mirror image.
The short broken lines around a perimeter of an outer pocket and an inner pocket in FIG. 1 are for the purpose of illustrating seam stitching.
The broken line showing of stitching in FIG. 1 is included for the purpose of illustrating portions of the article and forms no part of the claimed design.