Practicing some alternate active shoulder hangs on the pull-up bar. Great for grip, wrist, and forearm strength but mainly focusing on creating strength and stability in the shoulder joint for healthy shoulders and help reduce risk of shoulder injuries when performing other dynamic bodyweight exercises that can be hard on the shoulders. Give these a try and you'll soon find out which is your weaker and tighter side. Slow and controlled maintaining active shoulders, scapula down and back, as you alternate side to side grasping the pull-up bar. 

Performed on the MoveStrong pull-up bracket system with the Z-bar.