The ornamental design for a handle for a masonjar, as shown and described.
FIG. 1 is a top perspective view of a handle for a mason jar showing the design;
FIG. 2 is a top perspective view of the handle of FIG. 1 shown in use;
FIG. 3 is a top elevation view thereof of FIG. 1, the opposing bottom elevation view being a mirror image thereof;
FIG. 4 is a front elevation view of FIG. 1;
FIG. 5 is a rear elevation view of FIG. 1;
FIG. 6 is a side elevation view of FIG. 1; and,
FIG. 7 is an opposing side elevation view of FIG. 1.
The ornamental design which is claimed is shown in solid lines in the drawings. In the drawings, the broken lines depict environmental subject matter only that forms no part of the claim.