Steps:

1. Start off placing an extension band around a post or in a secure position where it will not release and is at elbow level.
2. Position yourself to the side of the band and with your hand that is opposite of the band, reach out and grab the handle.
3. Bring the band to your chest keeping your elbow bent in a 90 degree angle then slowly rotate your arm in a backhand motion so that the band externally rotates out
4. Continue out as far as possible so that you feel a stretch in your shoulders, hold for a count and then return back to the starting position.
5. Repeat for as many reps and sets as desired.

The diagram shows the most used muscles on this exercise