Teleportation grid

The Teleportation Grid is a Forerunner technology equipped to several important Installations.

Despite its name, the teleportation does not actually "teleport" its users - rather, it encases them in a compressed slipstream field, transporting them from one position to another almost instantaneously, much in the same way that a spaceship uses slipspace to travel between star systems - time passes for the individual, but due to the short distances involved it is negligible.

Both Installation 04 and Installation 05 were equipped with teleportation grids, allowing their Monitors to reach vital areas rapidly, and supervise their Sentinel charges. Though Onyx lacked a Monitor, it also possessed a teleportation grid.

Installation 04
Installation 04's teleportation grid was used extensively during the course of the Battle of Installation 04. The Installations Monitor, 343 Guilty Spark, first encountered the Master Chief outside of a Flood Research Facility in order to use the teleportationg rid to transport them to the Installation's Library, in order to retrieve the Activation Index. After the Index was retrieved, the Monitor used the grid again to transport the two of them to the Control Room, in order to activate the Halo Array. During the Master Chief's efforts to neutralise the Installation's primary firing sequence, Cortana tapped into the teleportation grid, using his Mark V MJOLNIR armor's fusion reactor to power a single jump to a downed Covenant cruiser - Cortana's relative inexperience with the grid resulted in reorientation difficulties.

Installation 05
Installation 05's teleportation grid was unavailable during the Battle of Installation 05, due to its use by the Gravemind, formed beneath that Installation's Library facility, through the Installation's captured Monitor, 2401 Penitent Tangent. Managing to ensnare both the Master Chief and the Arbiter, it formed a tentative alliance with the two enemies in order to stop the rings activation - teleporting the Master Chief aboard High Charity, in orbit above the Installation, and the Arbiter near the Control Room. The fact that it didn't, or couldn't, use the same grid to teleport its own Flood Combat Forms to those locations indicates that use of it is restricted to non-Flood lifeforms and constructs.

Onyx
The Shield World Onyx also possessed a teleportation grid, used by Doctor Halsey to transport the Spartan II's and III's to a safe area, away from Covenant activity. Later, she used it to send Spartan teams to disable a Sentinel production factory, before transporting them again to the center of the planet, to a portal leading to a Micro Dyson Sphere, as the Covenant were destroyed by nuclear warheads.