The EXVR-1 Guardian Grid, more frequently called the Ion Defense Grid, was essentially a complex system of ion field generators housed inside a large structure. These generators could focus their ionic power to create a single, powerful ionic blast. This blast was capable of disabling an enemy ship.
The passageway inside Exovar's Emporium that housed the Ion Defense Grid was locally referred to as "Ion Alley."
Paul Danner and Bill Smith conceived the Ion Defense Grid for Wretched Hives of Scum & Villainy. This was a sourcebook for the Star Wars: The Roleplaying Game, released by West End Games in 1997.
The grid appeared in the sourcebook as an example of the defensive systems used to protect Exovar's Emporium.