Plug in Unit

FIG. 1 is front view of a plug in unit. FIG. 2 is left side view of a plug in unit. FIG. 3 is right side view of a plug in unit. FIG. 4 is rear view of a plug in unit. FIG. 5 is top plan view of a plug in unit. FIG. 6 is bottom view of a plug in unit. FIG. 7 is a left-front perspective view of a plug in unit. FIG. 8 is an elevated left-front perspective view of a plug in unit; and, FIG. 9 is a left-front perspective view of a plug in unit in an open position. The broken lines in the drawings illustrate portions of a plug in unit that form no part of the claimed design.