US D589275 S1
The ornamental design for a stackable chair, as shown and described.
FIG. 1 is a perspective view of a stackable chair, looking toward the right front corner, showing my new design;
FIG. 2 is a right side elevation view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a bottom view thereof; and,
FIG. 7 is a perspective view of an alternate embodiment of the stackable chair shown in FIG. 1.