Civil Protection is the Combine's law enforcement agency on Earth, consisting of humans who have agreed to work on behalf of the Combine. Also referred to as metrocops, Civil Protection units wear light armor and gas masks, which heavily resemble a somewhat modified Soviet PMG mask. They are usually armed with electroshock batons and pistols, and are occasionally seen using MP-7 submachine guns. Metrocops are brutal in their methods, keeping the local populace in line via intimidation and physical force. Interrogations, inspections, raids, random beatings, summary executions and acts of extreme police brutality are all used as a means of policing their respective jurisdictions; their methods are justified by their role as "protectors of the civilians well-being". On the outskirts of City 17, Civil Protection units are observed patrolling for escapees from the city. Civil Protection officers are in constant contact with Combine Overwatch headquarters, which gives them objectives and situation updates. On the death of an officer, that officer's armor detects that its wearer is no longer alive and automatically informs headquarters of the fatality and advises nearby units as to the place of death.