As answers to other questions have explained, Bane wears a mask to provide pain management. The problem with this is quite simple:

The mask isn't attached to anything.

One would expect a tank of anesthetic gas or something connected by a hose, but there is no such reservoir, and no hoses leading anywhere except within the mask itself.

##How can a self contained mask with no external sources of anesthetic substances do anything to mitigate chronic pain? How does the mask work?