Keystone Coupler

FIG. 1 is a perspective view of a keystone coupler showing my new design;

FIG. 2 is another perspective view thereof;

FIG. 3 is a front view thereof, a rear view being a mirror image of the front view;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines depict portions of the keystone coupler that form no part of the claimed design.