[Yoda]

When Lynn is demonstrating the finish swivel for the swinger, on the impact bag, he is using the left arm.

When that is done with both hands on the club, what is powering the action? Pivot? left arm? right arm? All the above?

Good question, Chipingguru. Thanks!

Centrifugal Force -- driven by the Body's Transfer of Momentum Throw-Out Action (2-K, 2-M-4, 6-M-1) -- powers the Swinger's Finish Swivel. But, Swinging or Hitting, the Swivel Action is always a Left Forearm function (Sketches 2-K #4 and #5).

Remember, any Swivel Action is a true rotation of the Left Forearm and Wrist (indeed, the entire Left Arm Flying Wedge / 6-B-3-0-1). This as opposed to Horizontal or Angled Hinge Action (2-G) wherein the Wrists appear to Roll -- from Impact to the end of the Follow-Through / Both Arms Straight position -- but in reality are merely staying Vertical to either the Horizontal or Inclined Planes (and thereby producing respectively Clubface 'Close Only' or 'Close with Layback' Motions).

For example, the Release Swivel rotates the Left Wrist from its Turned condition ('palm down' to Plane) to its Vertical condition (at Impact) for Hinging. The Finish Swivel rotates the Left Wrist from its Vertical condition (at the end of the Follow-Through) to its Snap-Rolled condition ('palm up' to Plane) in preparation for the Finish.