The ornamental design for a kettlebell, as shown and described.
FIG. 1 is a top perspective view of a kettlebell showing our new design;
FIG. 2 is a front elevation view of the kettlebell of FIG. 1; the rear elevation view is a mirror image of the front view.
FIG. 3 is a right side elevation view of the kettlebell of FIG. 1; the left side elevation view is a mirror image of the right side; and,
FIG. 4 is a top plan view of the kettlebell of FIG. 1.
In the drawings, the evenly-spaced broken line showing a kettlebell depicts environment and forms no part of the claim. The dashed broken lines showing portions of the design in all figures are included for the purpose of illustrating environment and unclaimed features and form no part of the claimed design. The dot-dash broken lines showing portions of the design in all figures are included for the purpose of illustrating a boundary to areas marked by surface shading, and form no part of the claimed design.