The ornamental design for a buckle for bags, as shown and described.
FIG. 1 is a perspective view of a buckle for bags showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left-side view thereof;
FIG. 5 is a right-side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is an exploded perspective view of the buckle for bags; and,
FIG. 9 is a perspective view of the buckle for bags shown with environmental subject matter.
The broken lines in FIGS. 3, 4, and 5 show portions of the buckle for bags and form no part of the claimed design. The broken lines showing the fixing member in FIG. 9 depicts environmental subject matter and form no part of the claimed design.