The Arm Braid primarily provides support for the elbow in preventing hyperextension. It also reinforces the rotator cuff joint at the tip of the shoulder. Depending on how you wear it, It can give support for your wrist.
To benefit most shoulder issues, the Core Braid supports alignment for the entire shoulder girdle, stabilizing your shoulder blades onto you back. This is why it is important to spend time getting familiar with the Core Braid before adding the Arm Braid. They can be worn together or separately.