Inverted bent arm hang

This exercise is uncommon.
 

 - What are the prerequisites ? BL pull-ups & very good shoulder flexibility ?
- What are the benefits ? Does it lead somewhere in terms of GST ?
 
One arm bent arm hang :
 

It leads to reverse ice cream makers and some crazy shoulder flexibility.

That is nothing new, yoga practitioners have something similar called "Reverse prayer pose," or "Reverse namaste."

 

Plus something safer and similar is already part of the Foundation series.

 

Generally speaking reverse prayer pose is good for shoulder flexibility and better posture. 

 

With the way those behind the back bent arm hangs are being done, I wouldn't be surprised if someone completely dislocates their shoulder if not tears either their supraspinatus or infraspinatus tendon.