Put Wall Support is the strike with the largest net negative gamma in the underlying stock. 

Why does Put Wall Support matter?

This reveals where the largest hedge position is for the underlying positions.  

How to use Put Wall Support

If the Put Wall strike changes levels it can be an indication of large puts being shifted. If the Put Wall shifts to a higher strikes it’s could be a bearish indication, if it shifts to a lower strike it could be a bullish indication.