FIG. 1 is a perspective view of a blender showing a new design; FIG. 2 is front view thereof; FIG. 3 is a rear view thereof; FIG. 4 is a right side view thereof; FIG. 5 is a left side view thereof; FIG. 6 is a top plan view thereof; and, FIG. 7 is a bottom plan view thereof. The broken lines are for illustrative purposes only and form no part of the claimed design.