You can find this exercise on page 167 of the book Synergistic Golf.
Exercise Type: TOWEL
Exercise Category: FLEXIBILITY, HIPS, LEGS - FEET, POWER PRODUCTION, RHYTHM - TIMING
Stand tall with feet slightly wider than hip distance apart. Hold towel from ends in each hand directly in front of chest on a diagonal line. Inhale and reach towel to top left corner over shoulder slightly raising up on right toe. Exhale pulling towel with right hand down toward right ankle. Legs will bend into a slight lunge lifting left heel off floor. Focus on good form and rhythm. Repeat 10x on one side, Then switch to other side.