You can find this exercise on page 82 of the book Synergistic Golf.
Exercise Type: STRENGTH
Exercise Category: LEGS - FEET, LOW BACK, POWER PRODUCTION, RHYTHM - TIMING, STRENGTH
In wide stance, hold 3-5-8lb dumbbell in left hand. From impact position, follow through with left hand to balance finish position. Keep right shoulder down and flip right heel over. Then bring weight across and bending knees, reach across right foot. Repeat 20-30x with control.