The ornamental design for a self-retracting device, as shown and described.
FIG. 1 is a perspective view of a self-retracting device, showing our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left-side elevational view thereof, the right-side elevational view being a mirror image thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The broken lines showing an earbud cable in FIG. 1 depict environmental matter and form no part of the claimed design. The remaining broken lines depict portions of the self-retracting cable storage device that form no part of the claimed design.