You can find this exercise on page 101 of the book Synergistic Golf.
Exercise Type: STRENGTH
Exercise Category: SHOULDERS, STRENGTH
Stand tall with feet hip distance apart. Hold a 3-5-8lb dumbbell in each hand with elbows at right angles, arms against sides. Raise arms up until parallel to floor. Lower dumbbells to starting position. Repeat 10-15 repetitions for heavier weights; repeat 30-50x for lighter weights.