The ornamental design for a “closing device for chains,” as shown and described.
FIG. 1 is a front elevational view of the design, the rear elevational view being the same;
FIG. 2 is a top plan view of the design;
FIG. 3 is a bottom plan view of the design;
FIG. 4 is a side elevational view of the design taken from the left of FIG. 1, the side elevational view taken from the right of FIG. 1 being the same;
FIG. 5 is a perspective view of the design;
FIG. 6 is a front elevational view of the design, with the two elements thereof being spaced apart; and,
FIG. 7 is a perspective view of the design, with the two elements thereof being spaced apart.