The TKAD-4-E adapter makes installation of the TK4S-3X14-4 toekick a breeze. On the TK4S-3X14-6, the 4" tube needs to be forced into an elliptical shape to go over the end of the toekick exit. This can be a tough job. The TKAD-4-E mounts to the elliptical output end of the TK4S-3X14-6 toekick and provides a 4" round end to mount the flex-tube.