The ornamental design for a handle for a magnifier, as shown and described.
FIG. 1 is a perspective view of a handle for a magnifier showing our new design;
FIG. 2 is a another perspective view of the handle for a magnifier;
FIG. 3 is a top plan view of FIG. 1;
FIG. 4 is a bottom view of FIG. 1;
FIG. 5 is a first end elevational view of FIG. 1;
FIG. 6 is a second end elevational view of FIG. 1;
FIG. 7 is a right side elevational view of FIG. 1; and,
FIG. 8 is a left side elevational view of FIG. 1.
The dotted lines are intended to show features that are environmental only and form no part of the claimed design. Also, there is no intent to claim any surface indicia as all such surface lines are merely intended to be shading lines.