Don’t buy some fancy sticks that a company sells for $300 a bundle. Go to a Home Depot or Ace Hardware— and get yourself a pluming pipe for $3. I would grab two. There are simple, efficient ways to create end range mobility and stretching with 2 PVC pipes. This exercise is creating more shoulder external rotation. External rotation of the shoulder is vital for thoracic extension, holding the bar on the back, creating 180 degrees of flexion for lifting, throwing, and overall health of the glenohumeral and AC joints of the shoulder. I perform 5 repetitions minimum on each arm before I workout upper body, front rack positions, or throwing. Notice how I’m not dropping my shoulders to compensate for a lack of mobility. You most likely will not be able to drop the arm as low as this video. Practice practice, and be careful not to go to far.