The Combine use a large array of science fiction technologies. They have access to teleportation technology, which takes them from their dimension to other dimensions. However, their teleporter technology is restrictive in comparison to that developed by Eli Vance, Isaac Kleiner and Judith Mossman in that it cannot be used to teleport to other locations within a dimension, it can only be used to move between dimensions. Throughout the games, various futuristic computer consoles, doors, power sources and weapon emplacements are encountered. In addition, the Combine employ the use of small airborne robots, scanners, to observe the citizens of Earth. The city variant merely moves about the streets, monitors individuals, and takes photographs, while the combat equivalent is capable of dropping mines into an area. Civil Protection makes use of smaller airborne robots called manhacks, which fly using razor-sharp rotating blades with which they attack their targets to cause laceration injuries. These are often deployed in closed-in areas. The Combine also use two types of land mines; hopper mines throw themselves into the air and detonate when an enemy is detected nearby, while the spherical rollermines roll towards vehicles or other enemies, attach themselves and deliver damaging electrical attacks. Combine technology is also used to transform humans into Overwatch soldiers or stalkers, deformed and mutilated humans with no memory of their past selves who act as slaves and maintenance workers in Combine facilities. Transformation into a Stalker is considered among the Combine's worst punishments for dissidents.