Mark IV Patrol Droid
this series of repulsor-equipped sentries was created by Imperial Department of Military Research for use by the Empire shortly before the Battle of Yavin. They measured a third of a meter across, and moved about on a series of tiny repulsor-engines guided by several steering vanes. The Mark IV was unarmed, but carried a variety of sensors and recording devices to document the criminals it encountered. The Mark IV was also known as an IM IV droid, since they were manufactured for use by Imperial forces.