Dumbbell

FIG. 1 is a side perspective view of a dumbbell, showing my new design;

FIG. 2 is a top perspective view thereof, wherein the bottom perspective view is a mirror image thereof;

FIG. 3 is a right side view thereof, wherein the left side view is a mirror image thereof; and,

FIG. 4 is a front view thereof, wherein the back view is a mirror image thereof.

The broken line in the figures represent unclaimed subject matter and form no part of the claimed design.

The surface shading and contour lines shown in the drawings represent the three-dimensional character and contour of the article, and are not intended to illustrate material, surface ornamentation or surface decoration.