Set top box

FIG. 1 is a perspective view of an ornamental design for a set top box;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom thereof;

FIG. 4 is a first side view thereof;

FIG. 5 is a second side view thereof;

FIG. 6 is a rear view thereof; and,

FIG. 7 is a front view thereof.

The broken lines shown in FIGS. 1-7 , that are immediately adjacent to the shaded areas, and define unshaded regions, represent the bounds of the embodiment, while all other broken lines are directed to environment and are for illustrative purposes only; the broken lines form no part of the embodiment.