Blast Energy Sink
From Wookieepedia, the Star Wars wiki.
A Blast Energy Sink was a component of Stormtrooper armor.
Designed to reduce damage by reducing Blaster effect, it wasn't too efficient. Even with two of these, the chances of a Stormtrooper surviving was low. Often, the sinks failed to properly reduce damage from direct Blaster hits. Thus, large numbers of its wearers were left dead in numerous parts of the Galaxy.
