The battle droid assassin was a variation of the B1 battle droid used by the Trade Federation and the Confederacy of Independent Systems over the course of the the Clone Wars. Their gyroscopic stabilizers and detailed target-selection programs made them very effective snipers, which proved lethal to the Galactic Republic's clone troopers. They were not, however, as common as the regular B1 battle droids, because it was costly to make a droid as accurate as an organic sniper could be.