I claim the ornamental design for an exercise device universally attachable to a treadmill, as shown and described.
FIG. 1 is a front, side and top perspective view of the exercise device universally attachable to a treadmill with the roller pad rolled up for storage;
FIG. 2 is a front, side and top perspective view of the exercise device universally attachable to a treadmill with the roller pad rolled out for use and the foot element in an alternate position;
FIG. 3 is a front view of the exercise device universally attachable to a treadmill;
FIG. 4 is a bottom view of the exercise device universally attachable to a treadmill;
FIG. 5 is rear view of the exercise device universally attachable to a treadmill;
FIG. 6 is a top plan view of the exercise device universally attachable to a treadmill;
FIG. 7 is a side elevation view of the exercise device universally attachable to a treadmill; and,
FIG. 8 is an opposite side elevation view of the exercise device universally attachable to a treadmill.
The broken lines in FIGS. 1 and 2 illustrate environmental structure and form no part of the claimed design.