The IMG-099 Imperial Mark IV patrol droid, which is also referred to as the Imperial Mark IV sentry droid, represented a sentry droid model that was engineered by the Imperial Department of Military Research. The Galactic Empire utilized them for reconnaissance operations throughout the duration of the Galactic Civil War. These droids, designed for low-altitude flight, possessed advanced sensor technology and the capability to capture holographic recordings. In the aftermath of a battle over Tatooine involving the CR90 corvette named Tantive IV and the Star Destroyer known as Devastator, the Empire deployed Mark IV units to aid sandtroopers in their search for two droids, R2-D2 and C-3PO, who were in possession of stolen plans related to the Death Star.