FIG. 1 is a top, front, and right side perspective view of a coupler showing our new design;
FIG. 2 is a bottom, front, and left side perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a right side elevation view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The broken lines in the drawings illustrate portions of the coupler and form no part of the claimed design.