The ornamental design for a double-sided hair brush, as shown and described.
FIG. 1 is perspective view of a double-sided hair brush showing the new design;
FIG. 2 is a front end elevational view of the double-sided hair brush of FIG. 1;
FIG. 3 is a back end elevational view of the double-sided hair brush of FIG. 1;
FIG. 4 is a top plan view of the double-sided hair brush of FIG. 1;
FIG. 5 is a bottom plan view of the double-sided hair brush of FIG. 1; and,
FIG. 6 is a right side elevational view of the double-sided hair brush of FIG. 1, the left side elevation view is a mirror view of the right side elevation view.