Kah Mah Mahk Ki which means entangling block and not "spinning back fist" is comprised of the "hand over hand" movement where the hands rotate in a circle (either rolling up or down) that is evident in many of the Kuk Sool Won™ forms or "hyung." This dynamic strategy of defense requires less accurate timing than a single block when defending against an oncoming assault to the head or body.
Spinning Back Fist has been described as the most powerful hand technique available in the world of martial arts. When properly executed, and targetting the temple, KO and even death have resulted.
To perform a Spinning Back Fist, from offensive stance, turn in much the same way you would if performing Doh Rah Cha Ki, while simultaneously bringing your right fist up to your left temple. As you look over your right shoulder, allow your arm to follow, holding the fist thumb up. The striking surface is the back of the two first knuckles.