A Neural-Net eraser was a device used throughout the Clone Wars, as protection against rogue battle droids. These devices became a necessity for many beings who feared they would be attacked by the Separatist droids. When fired, it released a streak of blue energy that would destroy a droids internal circuitry and software, rendering them useless.
The servant droid Solis was shot by Asajj Ventress with a Neural-Net eraser, causing him to spasm and go out of control.