Combination Lock

FIG. 1 is a first perspective view of a combination lock showing my new design; FIG. 2 is a second perspective view thereof; FIG. 3 is a front view thereof; FIG. 4 is a back view thereof; FIG. 5 is a left side view thereof; FIG. 6 is a right side view thereof; FIG. 7 is a top view thereof; FIG. 8 is a bottom view thereof; and, FIG. 9 is an enlarged view of the selected portion 9 in FIG. 1 . The dash-dash broken lines shown in the drawings depict portions of the combination lock that form no part of the claimed design. The dot-dash broken lines in FIGS. 1 and 9 illustrate the periphery of the enlarged views of the combination lock and form no part of the claimed design.