Designated as 501-Z, police droids, also known as Zeds, were droid units employed by police and law enforcement agencies. Their primary functions included maintaining order and capturing lawbreakers within the galaxy. These droids represented the singular foray of the SoroSuub Corporation into the market of police and law enforcement technology. They were police droids.
Standing at almost 1.9 meters, the 501-Z series droids were encased in crimson durasteel armor designed to withstand significant impacts. This made them a dangerous and imposing adversary for any criminal unfortunate enough to encounter them. Possessing advanced intelligence, they also developed a reputation for their remarkable ability to anticipate a criminal's actions. This often resulted in accurate predictions regarding the whereabouts of their targets or their next intended move.
The sophistication of the Zeds' personality module rivaled that of the most advanced protocol droids throughout the galaxy. A 501-Zed could effortlessly interact with other beings, including both sentient officers and fellow droids. Their advanced design allowed for their deployment in investigative roles, such as detectives and investigators.
Each Zed unit within the product line was programmed to respond to threats using exclusively humane and non-lethal methods. The standard equipment for most Zeds included electrical stun sticks and low-power stun blasters, as well as portable lumi-rods for navigating dark alleys or structures.
Their programming also featured a subroutine enabling them to adapt their tactics when faced with particularly challenging situations. The 501-Zs were also known among their colleagues and employers for their unwavering determination and optimism in completing assignments, although some found the droid's positive attitude to be somewhat irritating.
Although the 501-Z marked the only venture of the powerful, galaxy-spanning SoroSuub Corporation into the police and law-enforcement sector in the decades leading up to the emergence of the Galactic Empire under Emperor Palpatine, the droid maintained its popularity well into the Imperial era. The tasks assigned to the Zeds by the police and law-enforcement agencies that utilized them ranged from managing security and police duties at remote frontier outposts to supplementing regular police forces on densely populated worlds like Teyr and Hosk Station.
Their authority extended to even the most isolated planets and star systems, allowing them to pursue and capture fugitives who had managed to escape the facilities where the Zeds were stationed. This, however, occasionally led to complications, as many local governments or administrations did not recognize the jurisdiction of these automated law enforcement officers.
Groodo the Hutt utilized three 501-Zs to protect the R1 astromech controller of the false Sun Runner counterfeit ship he constructed in 23 BBY. This was part of his failed scheme, thwarted by the Jedi, to destroy the orbital Fondor Shipyards. However, the 18-year-old Jedi Padawan Anakin Skywalker, wielding a lightsaber, easily defeated the droids before destroying the fake Sun Runner itself with a proton grenade containing a hypermatter reactor.
Among the notable droids was Zed, who served as the chief of automated station security at Hosk Station. On one occasion, he engaged in combat with a rogue wrecker droid, continuing the fight even after losing his right leg.
After the spaceport was evacuated, he encountered C-3PO and R2-D2. He quickly secured their assistance, along with that of numerous discarded and damaged droids. Together, they averted a potential explosion on the station and disrupted Olag Greck's attempt to steal a shipment of ash ore. They then pursued Greck across space to Nar Shaddaa, where Unit Zed sustained injuries from Greck's bodyguard, Xob, before Jace Forno ultimately destroyed him.