The Combine Civil Protection were the police of all cities owned by the combine, and they were the most un-modified units in the combine military. They had varied ranks, such as the Normal and Elite ranks. They were usually equipped with Stun Batons, Standard SMG's or Pistols.
They were varied in uniform depending on the rank.
They are considered Standard if they have just joined and have normal weapons and uniform. They have no special uniforms, and are commonly seen around the cities.
They are also seen in group raids, and sometimes guarding any combine barriers. They are the units most commonly seen with a Stun Baton.
They are like the Standard units, but will usually only have a Stun Baton, and they will also accompany Elite Civil Protection or just the ordinary standard units.
They have medical supplies at the ready, which can sometimes be bad if they are in groups.
They will rarely patrol on the streets unless necessary.
EliteThey are sometimes seen patrolling, and almost never use Stun Batons.
They have notably different uniforms, and usually stronger weaons.
They are usually more strict than normal CP units, and even "bully" lesser CP units around.
Stalkers are special units that are always in squads of 9 (ESS, Elite Stalker Squad), divided into 3 groups. There is 6 normal Stalkers, 2 Elite Stalkers, and the Leader. They are never patrolling the streets, always going on missions to destroy Resistance Bases, being replaced by the Alien Assassin if failure to complete their mission.If harmed while using invisibility, they will go back to normal, which is a disadvantage to their squad, as it is known they walk around in groups of 3.
They are very differently trained than normal Elites or Standard cops, as they control their invisibility with their mind, using Combine technology.
The Leaders usually have a manhack and a stronger weapon than others, and have brighter coloured uniforms.
They are Civil Protection units that specialize in Resistance raids. They are equipped with an M4, and a back-up AR2.