The Gemcutter, a device made by Carbanti United Electronics, was designed as an early model to disrupt the cloaking of ships while they were in hyperspace. This allowed the operator to know a ship's exit point from hyperspace, typically only about five seconds beforehand; however, as one person commented, "Those few seconds are the line between survival and demise."
Asajj Ventress, a Dark Jedi, absconded with the prototype and then integrated it into her lethal Ginivex-class starfighter, which was named the Last Call.