The 850.AA Public Service Headquarters was an integrated droid unit manufactured by Publictechnic that specialized in repulsorlift maintenance. Its primary function was to tackle the problem of urban decay.
The 850.AA model, a box-shaped maintenance and cleaning droid standing at a height of thirteen meters, was commonly deployed in major industrial zones found within the Core Worlds, the Colonies, and the Corporate Sector. While capable of hovering up to twenty meters above the ground using its repulsorlift technology, the droid typically operated at a height of one and a half meters to utilize its three abrasive scrubbers, which were mounted on its underside. These scrubbers worked alongside fourteen beamcleaners to precisely and powerfully clean streets.

Internally, the 850.AA was divided into three levels, each designed to accommodate various droids and equipment. The bottom level had the capacity to store up to thirty smaller droids, and it generally housed a complement of ten general-maintenance units, ten WED Treadwell repair droids, five worker drones, and five EG-6 power droids. To facilitate easy access, retractable ramps were incorporated into both sides of the 850.AA's durasteel exterior.
The second level of the 850.AA served as a parking area for two landspeeders or similar ground-based vehicles with a length of approximately ten meters. These vehicles were used by the Human crew members who operated the droid. An extensible ramp at the rear of the upper story provided an exit point for these vehicles.
The topmost level featured an open landing platform suitable for airspeeders and flitters. The front section of this level was equipped with a comprehensive sensor network designed to scan the surrounding environment for signs of urban decay. Furthermore, the 850.AA had the capability to deploy a number of specialized droids, maintaining communication with them through a focused tight-beam antennae, to perform more specific cleaning and repair tasks. The 850.AA provided recharging facilities for these support droids and could operate independently for extended periods of several weeks, thanks to its efficient energy-saving system.
It is documented that older 850.AA units were sometimes modified on certain planets to function as firefighting droids or construction units. One well-known incident on Carratos involved a street gang who commandeered an 850.AA, transforming it into a fortified hideout and a powerful battering ram.
- " Toria Tell's Droid Journal " — Star Wars Adventure Journal 10 (referred to as Model 850.AA Public Service Headquarters and Maintenance Droid)
- " Cynabar's Droid Datalog " — Star Wars Adventure Journal 14
- The Essential Guide to Droids
- The Official Star Wars Fact File 35 (TRE 1-2: 5T Tree Feeder)
- The Official Star Wars Fact File 103 (PUB 1-2: 850.AA Public Service Headquarters)
- The Complete Star Wars Encyclopedia