The ornamental design for a buckle, as shown and described.
FIG. 1 is a perspective view of a buckle showing my new design;
FIG. 2 is a front view of the buckle of FIG. 1;
FIG. 3 is a rear view of the buckle of FIG. 1;
FIG. 4 is a left side view of the buckle of FIG. 1;
FIG. 5 is a right side view of the buckle of FIG. 1;
FIG. 6 is a top view of the buckle of FIG. 1;
FIG. 7 is a bottom view of the buckle of FIG. 1;
FIG. 8 is a cross-sectional view taken along line A-A of FIG. 2;
FIG. 9 is a perspective view of the buckle of FIG. 1 shown with a connector buckle
FIG. 10 is another perspective view of the buckle of FIG. 1 shown with a connector buckle in a condition of use; and,
FIG. 11 is another perspective view of the buckle of FIG. 1 shown in a condition of use.
The broken lines shown in the drawings illustrate environmental structure that forms no part of the claimed design. The circle demarcating the claimed design in FIG. 11 forms no part of the claimed design.